diff --git a/.chronus/changes/deprecate-projected-name-2024-1-12-21-5-53.md b/.chronus/changes/deprecate-projected-name-2024-1-12-21-5-53.md
new file mode 100644
index 0000000000..2236f0634b
--- /dev/null
+++ b/.chronus/changes/deprecate-projected-name-2024-1-12-21-5-53.md
@@ -0,0 +1,14 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: deprecation
+packages:
+  - "@typespec/compiler"
+---
+
+Deprecate `@projectedName` decorator. `@encodedName` should be used instead.
+
+Example:
+```diff
+-@projectedName("json", "exp")
++@encodedName("application/json", "exp")
+```
diff --git a/.chronus/changes/deprecate-projected-name-2024-1-12-21-9-58.md b/.chronus/changes/deprecate-projected-name-2024-1-12-21-9-58.md
new file mode 100644
index 0000000000..957a83097d
--- /dev/null
+++ b/.chronus/changes/deprecate-projected-name-2024-1-12-21-9-58.md
@@ -0,0 +1,6 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: internal
+packages:
+  - "@typespec/openapi3"
+---
diff --git a/packages/compiler/lib/decorators.tsp b/packages/compiler/lib/decorators.tsp
index c40db4f1b2..4e8cf7a5be 100644
--- a/packages/compiler/lib/decorators.tsp
+++ b/packages/compiler/lib/decorators.tsp
@@ -366,6 +366,7 @@ extern dec overload(target: Operation, overloadbase: Operation);
  * }
  * ```
  */
+#deprecated "Use `@encodedName` instead for changing the name over the wire."
 extern dec projectedName(
   target: unknown,
   targetName: valueof string,
diff --git a/packages/compiler/test/projected-names.test.ts b/packages/compiler/test/projected-names.test.ts
index 4ea0bd3304..cf9418fc0a 100644
--- a/packages/compiler/test/projected-names.test.ts
+++ b/packages/compiler/test/projected-names.test.ts
@@ -13,6 +13,7 @@ describe("compiler: projected-names", () => {
   it("@projectName updates the name when running projection", async () => {
     const { expireAt } = (await runner.compile(`
       model Foo {
+        #suppress "deprecated" "for testing"
         @projectedName("json", "exp")
         @test expireAt: int32;
       }
@@ -24,6 +25,7 @@ describe("compiler: projected-names", () => {
   it("@projectName doesn't affect a different target", async () => {
     const { expireAt } = (await runner.compile(`
       model Foo {
+        #suppress "deprecated" "for testing"
         @projectedName("json", "exp")
         @test expireAt: int32;
       }
@@ -35,6 +37,7 @@ describe("compiler: projected-names", () => {
   it("can project to different targets", async () => {
     const { expireAt } = (await runner.compile(`
       model Foo {
+        #suppress "deprecated" "for testing"
         @projectedName("json", "exp")
         @projectedName("csharp", "ExpireAtCS")
         @test expireAt: int32;
@@ -49,6 +52,7 @@ describe("compiler: projected-names", () => {
   it("can project a different target on top of a projected one", async () => {
     const { expireAt } = (await runner.compile(`
       model Foo {
+        #suppress "deprecated" "for testing"
         @projectedName("json", "exp")
         @projectedName("csharp", "ExpireAtCS")
         @test expireAt: int32;
@@ -93,7 +97,9 @@ describe("compiler: projected-names", () => {
   it("projectedName overrides a previous renaming", async () => {
     const { expireAt, renamedProperty } = (await runner.compile(`
       model Foo {
+        #suppress "deprecated" "for testing"
         @projectedName("json", "jsonExpireAt") @test expireAt: int32;
+        #suppress "deprecated" "for testing"
         @projectedName("json", "jsonRenamedProperty") @test renamedProperty: string;
       }
 
diff --git a/packages/openapi3/test/models.test.ts b/packages/openapi3/test/models.test.ts
index 27d920de27..d5abc6659b 100644
--- a/packages/openapi3/test/models.test.ts
+++ b/packages/openapi3/test/models.test.ts
@@ -26,6 +26,7 @@ describe("openapi3: models", () => {
     const res = await oapiForModel(
       "Foo",
       `model Foo {
+        #suppress "deprecated" "for testing"
         @projectedName("json", "xJson")
         x: int32;
       };`
@@ -60,6 +61,7 @@ describe("openapi3: models", () => {
     const res = await oapiForModel(
       "Foo",
       `model Foo {
+        #suppress "deprecated" "for testing"
         @encodedName("application/json", "xJson")
         @projectedName("json", "projectedJson")
         x: int32;