diff --git a/lib/internal/main/embedding.js b/lib/internal/main/embedding.js
new file mode 100644
index 00000000000000..aa3f06cca10f99
--- /dev/null
+++ b/lib/internal/main/embedding.js
@@ -0,0 +1,18 @@
+'use strict';
+const {
+  prepareMainThreadExecution,
+  markBootstrapComplete,
+} = require('internal/process/pre_execution');
+const { isSea } = internalBinding('sea');
+const { emitExperimentalWarning } = require('internal/util');
+const { embedderRequire, embedderRunCjs } = require('internal/util/embedding');
+const { getEmbedderEntryFunction } = internalBinding('mksnapshot');
+
+prepareMainThreadExecution(false, true);
+markBootstrapComplete();
+
+if (isSea()) {
+  emitExperimentalWarning('Single executable application');
+}
+
+return getEmbedderEntryFunction()(embedderRequire, embedderRunCjs);
diff --git a/lib/internal/main/environment.js b/lib/internal/main/environment.js
deleted file mode 100644
index 0be982bfb6d25d..00000000000000
--- a/lib/internal/main/environment.js
+++ /dev/null
@@ -1,13 +0,0 @@
-'use strict';
-
-// This runs necessary preparations to prepare a complete Node.js context
-// that depends on run time states.
-// It is currently only intended for preparing contexts for embedders.
-
-const {
-  prepareMainThreadExecution,
-  markBootstrapComplete
-} = require('internal/process/pre_execution');
-
-prepareMainThreadExecution();
-markBootstrapComplete();
diff --git a/lib/internal/main/mksnapshot.js b/lib/internal/main/mksnapshot.js
index 928b3fd13f91d4..08d483dcff4e76 100644
--- a/lib/internal/main/mksnapshot.js
+++ b/lib/internal/main/mksnapshot.js
@@ -119,16 +119,25 @@ function main() {
   const {
     prepareMainThreadExecution
   } = require('internal/process/pre_execution');
+  const path = require('path');
 
   let serializeMainFunction = getEmbedderEntryFunction();
   const serializeMainArgs = [requireForUserSnapshot];
 
   if (serializeMainFunction) { // embedded case
     prepareMainThreadExecution(false, false);
+    // TODO(addaleax): Make this `embedderRunCjs` once require('module')
+    // is supported in snapshots.
+    const filename = process.execPath;
+    const dirname = path.dirname(filename);
+    function minimalRunCjs(source) {
+      const fn = compileSerializeMain(filename, source);
+      return fn(requireForUserSnapshot, filename, dirname);
+    }
+    serializeMainArgs.push(minimalRunCjs);
   } else {
     prepareMainThreadExecution(true, false);
     const file = process.argv[1];
-    const path = require('path');
     const filename = path.resolve(file);
     const dirname = path.dirname(filename);
     const source = readFileSync(file, 'utf-8');
diff --git a/lib/internal/main/single_executable_application.js b/lib/internal/main/single_executable_application.js
deleted file mode 100644
index d9604cff720d2f..00000000000000
--- a/lib/internal/main/single_executable_application.js
+++ /dev/null
@@ -1,55 +0,0 @@
-'use strict';
-const {
-  prepareMainThreadExecution,
-  markBootstrapComplete,
-} = require('internal/process/pre_execution');
-const { getSingleExecutableCode } = internalBinding('sea');
-const { emitExperimentalWarning } = require('internal/util');
-const { Module, wrapSafe } = require('internal/modules/cjs/loader');
-const { codes: { ERR_UNKNOWN_BUILTIN_MODULE } } = require('internal/errors');
-
-prepareMainThreadExecution(false, true);
-markBootstrapComplete();
-
-emitExperimentalWarning('Single executable application');
-
-// This is roughly the same as:
-//
-// const mod = new Module(filename);
-// mod._compile(contents, filename);
-//
-// but the code has been duplicated because currently there is no way to set the
-// value of require.main to module.
-//
-// TODO(RaisinTen): Find a way to deduplicate this.
-
-const filename = process.execPath;
-const contents = getSingleExecutableCode();
-const compiledWrapper = wrapSafe(filename, contents);
-
-const customModule = new Module(filename, null);
-customModule.filename = filename;
-customModule.paths = Module._nodeModulePaths(customModule.path);
-
-const customExports = customModule.exports;
-
-function customRequire(path) {
-  if (!Module.isBuiltin(path)) {
-    throw new ERR_UNKNOWN_BUILTIN_MODULE(path);
-  }
-
-  return require(path);
-}
-
-customRequire.main = customModule;
-
-const customFilename = customModule.filename;
-
-const customDirname = customModule.path;
-
-compiledWrapper(
-  customExports,
-  customRequire,
-  customModule,
-  customFilename,
-  customDirname);
diff --git a/lib/internal/util/embedding.js b/lib/internal/util/embedding.js
new file mode 100644
index 00000000000000..139d4c7a25fb7c
--- /dev/null
+++ b/lib/internal/util/embedding.js
@@ -0,0 +1,47 @@
+'use strict';
+const { codes: { ERR_UNKNOWN_BUILTIN_MODULE } } = require('internal/errors');
+const { Module, wrapSafe } = require('internal/modules/cjs/loader');
+
+// This is roughly the same as:
+//
+// const mod = new Module(filename);
+// mod._compile(contents, filename);
+//
+// but the code has been duplicated because currently there is no way to set the
+// value of require.main to module.
+//
+// TODO(RaisinTen): Find a way to deduplicate this.
+
+function embedderRunCjs(contents) {
+  const filename = process.execPath;
+  const compiledWrapper = wrapSafe(filename, contents);
+
+  const customModule = new Module(filename, null);
+  customModule.filename = filename;
+  customModule.paths = Module._nodeModulePaths(customModule.path);
+
+  const customExports = customModule.exports;
+
+  embedderRequire.main = customModule;
+
+  const customFilename = customModule.filename;
+
+  const customDirname = customModule.path;
+
+  return compiledWrapper(
+    customExports,
+    embedderRequire,
+    customModule,
+    customFilename,
+    customDirname);
+}
+
+function embedderRequire(path) {
+  if (!Module.isBuiltin(path)) {
+    throw new ERR_UNKNOWN_BUILTIN_MODULE(path);
+  }
+
+  return require(path);
+}
+
+module.exports = { embedderRequire, embedderRunCjs };
diff --git a/src/api/environment.cc b/src/api/environment.cc
index 3d3f864d4e956c..11243c70d5e16a 100644
--- a/src/api/environment.cc
+++ b/src/api/environment.cc
@@ -528,17 +528,15 @@ MaybeLocal<Value> LoadEnvironment(
   return StartExecution(env, cb);
 }
 
-MaybeLocal<Value> LoadEnvironment(
-    Environment* env,
-    const char* main_script_source_utf8) {
-  CHECK_NOT_NULL(main_script_source_utf8);
+MaybeLocal<Value> LoadEnvironment(Environment* env,
+                                  std::string_view main_script_source_utf8) {
+  CHECK_NOT_NULL(main_script_source_utf8.data());
   return LoadEnvironment(
       env, [&](const StartExecutionCallbackInfo& info) -> MaybeLocal<Value> {
-        std::string name = "embedder_main_" + std::to_string(env->thread_id());
-        env->builtin_loader()->Add(name.c_str(), main_script_source_utf8);
-        Realm* realm = env->principal_realm();
-
-        return realm->ExecuteBootstrapper(name.c_str());
+        Local<Value> main_script =
+            ToV8Value(env->context(), main_script_source_utf8).ToLocalChecked();
+        return info.run_cjs->Call(
+            env->context(), Null(env->isolate()), 1, &main_script);
       });
 }
 
diff --git a/src/env-inl.h b/src/env-inl.h
index 6b4d63616abe39..8d17a0ae4f6282 100644
--- a/src/env-inl.h
+++ b/src/env-inl.h
@@ -406,14 +406,12 @@ inline builtins::BuiltinLoader* Environment::builtin_loader() {
   return &builtin_loader_;
 }
 
-inline const StartExecutionCallback&
-Environment::embedder_mksnapshot_entry_point() const {
-  return embedder_mksnapshot_entry_point_;
+inline const StartExecutionCallback& Environment::embedder_entry_point() const {
+  return embedder_entry_point_;
 }
 
-inline void Environment::set_embedder_mksnapshot_entry_point(
-    StartExecutionCallback&& fn) {
-  embedder_mksnapshot_entry_point_ = std::move(fn);
+inline void Environment::set_embedder_entry_point(StartExecutionCallback&& fn) {
+  embedder_entry_point_ = std::move(fn);
 }
 
 inline double Environment::new_async_id() {
diff --git a/src/env.h b/src/env.h
index 629b99a9205069..0f27e105e4af2a 100644
--- a/src/env.h
+++ b/src/env.h
@@ -946,8 +946,8 @@ class Environment : public MemoryRetainer {
 
 #endif  // HAVE_INSPECTOR
 
-  inline const StartExecutionCallback& embedder_mksnapshot_entry_point() const;
-  inline void set_embedder_mksnapshot_entry_point(StartExecutionCallback&& fn);
+  inline const StartExecutionCallback& embedder_entry_point() const;
+  inline void set_embedder_entry_point(StartExecutionCallback&& fn);
 
   inline void set_process_exit_handler(
       std::function<void(Environment*, ExitCode)>&& handler);
@@ -1131,7 +1131,7 @@ class Environment : public MemoryRetainer {
   std::unique_ptr<Realm> principal_realm_ = nullptr;
 
   builtins::BuiltinLoader builtin_loader_;
-  StartExecutionCallback embedder_mksnapshot_entry_point_;
+  StartExecutionCallback embedder_entry_point_;
 
   // Used by allocate_managed_buffer() and release_managed_buffer() to keep
   // track of the BackingStore for a given pointer.
diff --git a/src/node.cc b/src/node.cc
index 0d5162dde5da88..00fe99aaba165b 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -277,22 +277,17 @@ MaybeLocal<Value> StartExecution(Environment* env, StartExecutionCallback cb) {
 
   if (cb != nullptr) {
     EscapableHandleScope scope(env->isolate());
+    // TODO(addaleax): pass the callback to the main script more directly,
+    // e.g. by making StartExecution(env, builtin) parametrizable
+    env->set_embedder_entry_point(std::move(cb));
+    auto reset_entry_point =
+        OnScopeLeave([&]() { env->set_embedder_entry_point({}); });
 
-    if (env->isolate_data()->options()->build_snapshot) {
-      // TODO(addaleax): pass the callback to the main script more directly,
-      // e.g. by making StartExecution(env, builtin) parametrizable
-      env->set_embedder_mksnapshot_entry_point(std::move(cb));
-      auto reset_entry_point =
-          OnScopeLeave([&]() { env->set_embedder_mksnapshot_entry_point({}); });
+    const char* entry = env->isolate_data()->options()->build_snapshot
+                            ? "internal/main/mksnapshot"
+                            : "internal/main/embedding";
 
-      return StartExecution(env, "internal/main/mksnapshot");
-    }
-
-    if (StartExecution(env, "internal/main/environment").IsEmpty()) return {};
-    return scope.EscapeMaybe(cb({
-        env->process_object(),
-        env->builtin_module_require(),
-    }));
+    return scope.EscapeMaybe(StartExecution(env, entry));
   }
 
   // TODO(joyeecheung): move these conditions into JS land and let the
@@ -312,18 +307,6 @@ MaybeLocal<Value> StartExecution(Environment* env, StartExecutionCallback cb) {
     first_argv = env->argv()[1];
   }
 
-#ifndef DISABLE_SINGLE_EXECUTABLE_APPLICATION
-  if (sea::IsSingleExecutable()) {
-    // TODO(addaleax): Find a way to reuse:
-    //
-    // LoadEnvironment(Environment*, const char*)
-    //
-    // instead and not add yet another main entry point here because this
-    // already duplicates existing code.
-    return StartExecution(env, "internal/main/single_executable_application");
-  }
-#endif
-
   if (first_argv == "inspect") {
     return StartExecution(env, "internal/main/inspect");
   }
diff --git a/src/node.h b/src/node.h
index 635e5349f4ee88..c3a81076d54ed6 100644
--- a/src/node.h
+++ b/src/node.h
@@ -682,6 +682,7 @@ NODE_EXTERN std::unique_ptr<InspectorParentHandle> GetInspectorParentHandle(
 struct StartExecutionCallbackInfo {
   v8::Local<v8::Object> process_object;
   v8::Local<v8::Function> native_require;
+  v8::Local<v8::Function> run_cjs;
 };
 
 using StartExecutionCallback =
@@ -691,8 +692,7 @@ NODE_EXTERN v8::MaybeLocal<v8::Value> LoadEnvironment(
     Environment* env,
     StartExecutionCallback cb);
 NODE_EXTERN v8::MaybeLocal<v8::Value> LoadEnvironment(
-    Environment* env,
-    const char* main_script_source_utf8);
+    Environment* env, std::string_view main_script_source_utf8);
 NODE_EXTERN void FreeEnvironment(Environment* env);
 
 // Set a callback that is called when process.exit() is called from JS,
diff --git a/src/node_builtins.cc b/src/node_builtins.cc
index e9bf8a5a0e0b7e..0439fff5115bd9 100644
--- a/src/node_builtins.cc
+++ b/src/node_builtins.cc
@@ -185,17 +185,14 @@ static std::string OnDiskFileName(const char* id) {
 MaybeLocal<String> BuiltinLoader::LoadBuiltinSource(Isolate* isolate,
                                                     const char* id) const {
   auto source = source_.read();
-#ifdef NODE_BUILTIN_MODULES_PATH
-  if (strncmp(id, "embedder_main_", strlen("embedder_main_")) == 0) {
-#endif  // NODE_BUILTIN_MODULES_PATH
-    const auto source_it = source->find(id);
-    if (UNLIKELY(source_it == source->end())) {
-      fprintf(stderr, "Cannot find native builtin: \"%s\".\n", id);
-      ABORT();
-    }
-    return source_it->second.ToStringChecked(isolate);
-#ifdef NODE_BUILTIN_MODULES_PATH
+#ifndef NODE_BUILTIN_MODULES_PATH
+  const auto source_it = source->find(id);
+  if (UNLIKELY(source_it == source->end())) {
+    fprintf(stderr, "Cannot find native builtin: \"%s\".\n", id);
+    ABORT();
   }
+  return source_it->second.ToStringChecked(isolate);
+#else   // !NODE_BUILTIN_MODULES_PATH
   std::string filename = OnDiskFileName(id);
 
   std::string contents;
@@ -395,12 +392,6 @@ MaybeLocal<Function> BuiltinLoader::LookupAndCompile(Local<Context> context,
         FIXED_ONE_BYTE_STRING(isolate, "internalBinding"),
         FIXED_ONE_BYTE_STRING(isolate, "primordials"),
     };
-  } else if (strncmp(id, "embedder_main_", strlen("embedder_main_")) == 0) {
-    // Synthetic embedder main scripts from LoadEnvironment(): process, require
-    parameters = {
-        FIXED_ONE_BYTE_STRING(isolate, "process"),
-        FIXED_ONE_BYTE_STRING(isolate, "require"),
-    };
   } else {
     // others: exports, require, module, process, internalBinding, primordials
     parameters = {
@@ -457,12 +448,6 @@ MaybeLocal<Value> BuiltinLoader::CompileAndCall(Local<Context> context,
                  realm->builtin_module_require(),
                  realm->internal_binding_loader(),
                  realm->primordials()};
-  } else if (strncmp(id, "embedder_main_", strlen("embedder_main_")) == 0) {
-    // Synthetic embedder main scripts from LoadEnvironment(): process, require
-    arguments = {
-        realm->process_object(),
-        realm->builtin_module_require(),
-    };
   } else {
     // This should be invoked with the other CompileAndCall() methods, as
     // we are unable to generate the arguments.
diff --git a/src/node_main_instance.cc b/src/node_main_instance.cc
index 5a4d127ffe3e43..f0dc6ca275b007 100644
--- a/src/node_main_instance.cc
+++ b/src/node_main_instance.cc
@@ -9,6 +9,7 @@
 #include "node_internals.h"
 #include "node_options-inl.h"
 #include "node_realm.h"
+#include "node_sea.h"
 #include "node_snapshot_builder.h"
 #include "node_snapshotable.h"
 #include "node_v8_platform-inl.h"
@@ -86,7 +87,16 @@ ExitCode NodeMainInstance::Run() {
 
 void NodeMainInstance::Run(ExitCode* exit_code, Environment* env) {
   if (*exit_code == ExitCode::kNoFailure) {
-    LoadEnvironment(env, StartExecutionCallback{});
+    bool is_sea = false;
+#ifndef DISABLE_SINGLE_EXECUTABLE_APPLICATION
+    if (sea::IsSingleExecutable()) {
+      is_sea = true;
+      LoadEnvironment(env, sea::FindSingleExecutableCode());
+    }
+#endif
+    if (!is_sea) {
+      LoadEnvironment(env, StartExecutionCallback{});
+    }
 
     *exit_code =
         SpinEventLoopInternal(env).FromMaybe(ExitCode::kGenericUserError);
diff --git a/src/node_sea.cc b/src/node_sea.cc
index 18b661ce4ff31d..b65620d1ff9684 100644
--- a/src/node_sea.cc
+++ b/src/node_sea.cc
@@ -4,8 +4,6 @@
 #include "node_external_reference.h"
 #include "node_internals.h"
 #include "node_union_bytes.h"
-#include "simdutf.h"
-#include "v8.h"
 
 // The POSTJECT_SENTINEL_FUSE macro is a string of random characters selected by
 // the Node.js project that is present only once in the entire binary. It is
@@ -19,7 +17,6 @@
 #include <memory>
 #include <string_view>
 #include <tuple>
-#include <vector>
 
 #if !defined(DISABLE_SINGLE_EXECUTABLE_APPLICATION)
 
@@ -29,9 +26,11 @@ using v8::Local;
 using v8::Object;
 using v8::Value;
 
-namespace {
+namespace node {
+namespace sea {
 
-const std::string_view FindSingleExecutableCode() {
+std::string_view FindSingleExecutableCode() {
+  CHECK(IsSingleExecutable());
   static const std::string_view sea_code = []() -> std::string_view {
     size_t size;
 #ifdef __APPLE__
@@ -49,44 +48,14 @@ const std::string_view FindSingleExecutableCode() {
   return sea_code;
 }
 
-void GetSingleExecutableCode(const FunctionCallbackInfo<Value>& args) {
-  node::Environment* env = node::Environment::GetCurrent(args);
-
-  static const std::string_view sea_code = FindSingleExecutableCode();
-
-  if (sea_code.empty()) {
-    return;
-  }
-
-  // TODO(joyeecheung): Use one-byte strings for ASCII-only source to save
-  // memory/binary size - using UTF16 by default results in twice of the size
-  // than necessary.
-  static const node::UnionBytes sea_code_union_bytes =
-      []() -> node::UnionBytes {
-    size_t expected_u16_length =
-        simdutf::utf16_length_from_utf8(sea_code.data(), sea_code.size());
-    auto out = std::make_shared<std::vector<uint16_t>>(expected_u16_length);
-    size_t u16_length = simdutf::convert_utf8_to_utf16(
-        sea_code.data(),
-        sea_code.size(),
-        reinterpret_cast<char16_t*>(out->data()));
-    out->resize(u16_length);
-    return node::UnionBytes{out};
-  }();
-
-  args.GetReturnValue().Set(
-      sea_code_union_bytes.ToStringChecked(env->isolate()));
-}
-
-}  // namespace
-
-namespace node {
-namespace sea {
-
 bool IsSingleExecutable() {
   return postject_has_resource();
 }
 
+void IsSingleExecutable(const FunctionCallbackInfo<Value>& args) {
+  args.GetReturnValue().Set(IsSingleExecutable());
+}
+
 std::tuple<int, char**> FixupArgsForSEA(int argc, char** argv) {
   // Repeats argv[0] at position 1 on argv as a replacement for the missing
   // entry point file path.
@@ -113,12 +82,11 @@ void Initialize(Local<Object> target,
                 Local<Value> unused,
                 Local<Context> context,
                 void* priv) {
-  SetMethod(
-      context, target, "getSingleExecutableCode", GetSingleExecutableCode);
+  SetMethod(context, target, "isSea", IsSingleExecutable);
 }
 
 void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
-  registry->Register(GetSingleExecutableCode);
+  registry->Register(IsSingleExecutable);
 }
 
 }  // namespace sea
diff --git a/src/node_sea.h b/src/node_sea.h
index 97bf0115e0f0d4..aa0f20204743c0 100644
--- a/src/node_sea.h
+++ b/src/node_sea.h
@@ -5,12 +5,14 @@
 
 #if !defined(DISABLE_SINGLE_EXECUTABLE_APPLICATION)
 
+#include <string_view>
 #include <tuple>
 
 namespace node {
 namespace sea {
 
 bool IsSingleExecutable();
+std::string_view FindSingleExecutableCode();
 std::tuple<int, char**> FixupArgsForSEA(int argc, char** argv);
 
 }  // namespace sea
diff --git a/src/node_snapshotable.cc b/src/node_snapshotable.cc
index d9d4f162e9cfd2..b4d8174c4f50e0 100644
--- a/src/node_snapshotable.cc
+++ b/src/node_snapshotable.cc
@@ -1443,19 +1443,25 @@ void SerializeSnapshotableObjects(Realm* realm,
 
 namespace mksnapshot {
 
+// NB: This is also used by the regular embedding codepath.
 void GetEmbedderEntryFunction(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   Isolate* isolate = env->isolate();
-  if (!env->embedder_mksnapshot_entry_point()) return;
+  if (!env->embedder_entry_point()) return;
   MaybeLocal<Function> jsfn =
       Function::New(isolate->GetCurrentContext(),
                     [](const FunctionCallbackInfo<Value>& args) {
                       Environment* env = Environment::GetCurrent(args);
                       Local<Value> require_fn = args[0];
+                      Local<Value> runcjs_fn = args[1];
                       CHECK(require_fn->IsFunction());
-                      CHECK(env->embedder_mksnapshot_entry_point());
-                      env->embedder_mksnapshot_entry_point()(
-                          {env->process_object(), require_fn.As<Function>()});
+                      CHECK(runcjs_fn->IsFunction());
+                      MaybeLocal<Value> retval = env->embedder_entry_point()(
+                          {env->process_object(),
+                           require_fn.As<Function>(),
+                           runcjs_fn.As<Function>()});
+                      if (!retval.IsEmpty())
+                        args.GetReturnValue().Set(retval.ToLocalChecked());
                     });
   if (!jsfn.IsEmpty()) args.GetReturnValue().Set(jsfn.ToLocalChecked());
 }
diff --git a/test/embedding/test-embedding.js b/test/embedding/test-embedding.js
index 498c05fdebf377..9dfaad6c2ab27f 100644
--- a/test/embedding/test-embedding.js
+++ b/test/embedding/test-embedding.js
@@ -40,6 +40,11 @@ assert.strictEqual(
   child_process.spawnSync(binary, ['throw new Error()']).status,
   1);
 
+// Cannot require internals anymore:
+assert.strictEqual(
+  child_process.spawnSync(binary, ['require("lib/internal/test/binding")']).status,
+  1);
+
 assert.strictEqual(
   child_process.spawnSync(binary, ['process.exitCode = 8']).status,
   8);