diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1bc2c7ac2da..3b3b2379395 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 - Add frames delay to transactions and spans (#3487, #3496)
 - Add slow and frozen frames to spans (#3450, #3478)
+- Split up UIKit and App Init App Start Span (#3534)
 - Prewarmed App Start Tracing is stable (#3536)
 
 ### Fixes
diff --git a/Sources/Sentry/SentryAppStartMeasurement.m b/Sources/Sentry/SentryAppStartMeasurement.m
index 6649a250604..8c87356a6d4 100644
--- a/Sources/Sentry/SentryAppStartMeasurement.m
+++ b/Sources/Sentry/SentryAppStartMeasurement.m
@@ -15,6 +15,7 @@ @implementation SentryAppStartMeasurement
     NSDate *_appStartTimestamp;
     NSDate *_runtimeInitTimestamp;
     NSDate *_moduleInitializationTimestamp;
+    NSDate *_sdkStartTimestamp;
     NSDate *_didFinishLaunchingTimestamp;
 }
 #    endif // SENTRY_HAS_UIKIT
@@ -25,6 +26,7 @@ - (instancetype)initWithType:(SentryAppStartType)type
                          duration:(NSTimeInterval)duration
              runtimeInitTimestamp:(NSDate *)runtimeInitTimestamp
     moduleInitializationTimestamp:(NSDate *)moduleInitializationTimestamp
+                sdkStartTimestamp:(NSDate *)sdkStartTimestamp
       didFinishLaunchingTimestamp:(NSDate *)didFinishLaunchingTimestamp
 {
 #    if SENTRY_HAS_UIKIT
@@ -35,6 +37,7 @@ - (instancetype)initWithType:(SentryAppStartType)type
         _duration = duration;
         _runtimeInitTimestamp = runtimeInitTimestamp;
         _moduleInitializationTimestamp = moduleInitializationTimestamp;
+        _sdkStartTimestamp = sdkStartTimestamp;
         _didFinishLaunchingTimestamp = didFinishLaunchingTimestamp;
     }
 
diff --git a/Sources/Sentry/SentryAppStartTracker.m b/Sources/Sentry/SentryAppStartTracker.m
index 2786ad66b14..38da3d0f286 100644
--- a/Sources/Sentry/SentryAppStartTracker.m
+++ b/Sources/Sentry/SentryAppStartTracker.m
@@ -216,6 +216,7 @@ - (void)buildAppStartMeasurement:(NSDate *)appStartEnd
                                                    duration:appStartDuration
                                        runtimeInitTimestamp:runtimeInit
                               moduleInitializationTimestamp:sysctl.moduleInitializationTimestamp
+                                          sdkStartTimestamp:SentrySDK.startTimestamp
                                 didFinishLaunchingTimestamp:self.didFinishLaunchingTimestamp];
 
         SentrySDK.appStartMeasurement = appStartMeasurement;
diff --git a/Sources/Sentry/SentryBuildAppStartSpans.m b/Sources/Sentry/SentryBuildAppStartSpans.m
index bfa40a5280f..2d344bef1b1 100644
--- a/Sources/Sentry/SentryBuildAppStartSpans.m
+++ b/Sources/Sentry/SentryBuildAppStartSpans.m
@@ -74,12 +74,18 @@
         [appStartSpans addObject:runtimeInitSpan];
     }
 
-    SentrySpan *appInitSpan = sentryBuildAppStartSpan(
-        tracer, appStartSpan.spanId, operation, @"UIKit and Application Init");
+    SentrySpan *appInitSpan
+        = sentryBuildAppStartSpan(tracer, appStartSpan.spanId, operation, @"UIKit Init");
     [appInitSpan setStartTimestamp:appStartMeasurement.moduleInitializationTimestamp];
-    [appInitSpan setTimestamp:appStartMeasurement.didFinishLaunchingTimestamp];
+    [appInitSpan setTimestamp:appStartMeasurement.sdkStartTimestamp];
     [appStartSpans addObject:appInitSpan];
 
+    SentrySpan *didFinishLaunching
+        = sentryBuildAppStartSpan(tracer, appStartSpan.spanId, operation, @"Application Init");
+    [didFinishLaunching setStartTimestamp:appStartMeasurement.sdkStartTimestamp];
+    [didFinishLaunching setTimestamp:appStartMeasurement.didFinishLaunchingTimestamp];
+    [appStartSpans addObject:didFinishLaunching];
+
     SentrySpan *frameRenderSpan
         = sentryBuildAppStartSpan(tracer, appStartSpan.spanId, operation, @"Initial Frame Render");
     [frameRenderSpan setStartTimestamp:appStartMeasurement.didFinishLaunchingTimestamp];
diff --git a/Sources/Sentry/SentrySDK.m b/Sources/Sentry/SentrySDK.m
index 2840b439a1b..4135697d259 100644
--- a/Sources/Sentry/SentrySDK.m
+++ b/Sources/Sentry/SentrySDK.m
@@ -7,6 +7,7 @@
 #import "SentryClient+Private.h"
 #import "SentryCrash.h"
 #import "SentryCrashWrapper.h"
+#import "SentryCurrentDateProvider.h"
 #import "SentryDependencyContainer.h"
 #import "SentryDispatchQueueWrapper.h"
 #import "SentryFileManager.h"
@@ -42,6 +43,7 @@ @implementation SentrySDK
  * reenable the integrations.
  */
 static NSUInteger startInvocations;
+static NSDate *_Nullable startTimestamp = nil;
 
 + (void)initialize
 {
@@ -135,6 +137,22 @@ + (void)setStartInvocations:(NSUInteger)value
     startInvocations = value;
 }
 
+/**
+ * Not public, only for internal use.
+ */
++ (nullable NSDate *)startTimestamp
+{
+    return startTimestamp;
+}
+
+/**
+ * Only needed for testing.
+ */
++ (void)setStartTimestamp:(NSDate *)value
+{
+    startTimestamp = value;
+}
+
 + (void)startWithOptions:(SentryOptions *)options
 {
     [SentryLog configure:options.debug diagnosticLevel:options.diagnosticLevel];
@@ -145,6 +163,7 @@ + (void)startWithOptions:(SentryOptions *)options
     SENTRY_LOG_DEBUG(@"Starting SDK...");
 
     startInvocations++;
+    startTimestamp = [SentryDependencyContainer.sharedInstance.dateProvider date];
 
     SentryClient *newClient = [[SentryClient alloc] initWithOptions:options];
     [newClient.fileManager moveAppStateToPreviousAppState];
@@ -402,6 +421,8 @@ + (void)close
 {
     SENTRY_LOG_DEBUG(@"Starting to close SDK.");
 
+    startTimestamp = nil;
+
     SentryHub *hub = SentrySDK.currentHub;
     [hub removeAllIntegrations];
 
diff --git a/Sources/Sentry/include/HybridPublic/SentryAppStartMeasurement.h b/Sources/Sentry/include/HybridPublic/SentryAppStartMeasurement.h
index f48cdd5f370..edd879dca9a 100644
--- a/Sources/Sentry/include/HybridPublic/SentryAppStartMeasurement.h
+++ b/Sources/Sentry/include/HybridPublic/SentryAppStartMeasurement.h
@@ -26,6 +26,7 @@ SENTRY_NO_INIT
                          duration:(NSTimeInterval)duration
              runtimeInitTimestamp:(NSDate *)runtimeInitTimestamp
     moduleInitializationTimestamp:(NSDate *)moduleInitializationTimestamp
+                sdkStartTimestamp:(NSDate *)sdkStartTimestamp
       didFinishLaunchingTimestamp:(NSDate *)didFinishLaunchingTimestamp;
 
 /**
@@ -58,6 +59,11 @@ SENTRY_NO_INIT
  */
 @property (readonly, nonatomic, strong) NSDate *moduleInitializationTimestamp;
 
+/**
+ * When the SentrySDK start method is called.
+ */
+@property (readonly, nonatomic, strong) NSDate *sdkStartTimestamp;
+
 /**
  * When OS posts UIApplicationDidFinishLaunchingNotification.
  */
diff --git a/Sources/Sentry/include/SentrySDK+Private.h b/Sources/Sentry/include/SentrySDK+Private.h
index de0f263286f..9d0f728acca 100644
--- a/Sources/Sentry/include/SentrySDK+Private.h
+++ b/Sources/Sentry/include/SentrySDK+Private.h
@@ -21,6 +21,7 @@ SentrySDK ()
 + (nullable SentryAppStartMeasurement *)getAppStartMeasurement;
 
 @property (nonatomic, class) NSUInteger startInvocations;
+@property (nullable, nonatomic, class) NSDate *startTimestamp;
 
 + (SentryHub *)currentHub;
 
diff --git a/Tests/SentryProfilerTests/SentryProfilerSwiftTests.swift b/Tests/SentryProfilerTests/SentryProfilerSwiftTests.swift
index 8ed4b6c5a20..f7c8d938ed8 100644
--- a/Tests/SentryProfilerTests/SentryProfilerSwiftTests.swift
+++ b/Tests/SentryProfilerTests/SentryProfilerSwiftTests.swift
@@ -228,7 +228,8 @@ class SentryProfilerSwiftTests: XCTestCase {
             appStart = preWarmed ? main : appStart
             appStartDuration = preWarmed ? appStartDuration - runtimeInitDuration - mainDuration : appStartDuration
             appStartEnd = appStart.addingTimeInterval(appStartDuration)
-            return SentryAppStartMeasurement(type: type, isPreWarmed: preWarmed, appStartTimestamp: appStart, duration: appStartDuration, runtimeInitTimestamp: runtimeInit, moduleInitializationTimestamp: main, didFinishLaunchingTimestamp: didFinishLaunching)
+            return SentryAppStartMeasurement(type: type, isPreWarmed: preWarmed, appStartTimestamp: appStart, duration: appStartDuration, runtimeInitTimestamp: runtimeInit, moduleInitializationTimestamp: main,
+                                             sdkStartTimestamp: appStart, didFinishLaunchingTimestamp: didFinishLaunching)
         }
         #endif // os(iOS) || os(tvOS) || targetEnvironment(macCatalyst)
     }
diff --git a/Tests/SentryTests/Integrations/Performance/AppStartTracking/SentryAppStartTrackerTests.swift b/Tests/SentryTests/Integrations/Performance/AppStartTracking/SentryAppStartTrackerTests.swift
index 8e4bd5d73e9..18106d87d0d 100644
--- a/Tests/SentryTests/Integrations/Performance/AppStartTracking/SentryAppStartTrackerTests.swift
+++ b/Tests/SentryTests/Integrations/Performance/AppStartTracking/SentryAppStartTrackerTests.swift
@@ -24,6 +24,7 @@ class SentryAppStartTrackerTests: NotificationCenterTestCase {
         let appStartDuration: TimeInterval = 0.4
         var runtimeInitTimestamp: Date
         var moduleInitializationTimestamp: Date
+        var sdkStartTimestamp: Date
         var didFinishLaunchingTimestamp: Date
         
         init() {
@@ -50,7 +51,10 @@ class SentryAppStartTrackerTests: NotificationCenterTestCase {
             
             runtimeInitTimestamp = SentryDependencyContainer.sharedInstance().dateProvider.date().addingTimeInterval(0.2)
             moduleInitializationTimestamp = SentryDependencyContainer.sharedInstance().dateProvider.date().addingTimeInterval(0.1)
-            didFinishLaunchingTimestamp = SentryDependencyContainer.sharedInstance().dateProvider.date().addingTimeInterval(0.3)
+            sdkStartTimestamp = SentryDependencyContainer.sharedInstance().dateProvider.date().addingTimeInterval(0.1)
+            SentrySDK.startTimestamp = sdkStartTimestamp
+            
+            didFinishLaunchingTimestamp = SentryDependencyContainer.sharedInstance().dateProvider.date().addingTimeInterval(0.2)
         }
         
         var sut: SentryAppStartTracker {
@@ -440,10 +444,12 @@ class SentryAppStartTrackerTests: NotificationCenterTestCase {
             XCTAssertEqual(fixture.sysctl.processStartTimestamp, appStartMeasurement.appStartTimestamp)
         }
 
-        XCTAssertEqual(fixture.sysctl.moduleInitializationTimestamp, appStartMeasurement.moduleInitializationTimestamp)
-        XCTAssertEqual(fixture.runtimeInitTimestamp, appStartMeasurement.runtimeInitTimestamp)
-        XCTAssertEqual(fixture.didFinishLaunchingTimestamp, appStartMeasurement.didFinishLaunchingTimestamp)
-        XCTAssertEqual(preWarmed, appStartMeasurement.isPreWarmed)
+        expect(appStartMeasurement.moduleInitializationTimestamp) == fixture.sysctl.moduleInitializationTimestamp
+        expect(appStartMeasurement.runtimeInitTimestamp) == fixture.runtimeInitTimestamp
+        
+        expect(appStartMeasurement.sdkStartTimestamp) == fixture.sdkStartTimestamp
+        expect(appStartMeasurement.didFinishLaunchingTimestamp) == fixture.didFinishLaunchingTimestamp
+        expect(appStartMeasurement.isPreWarmed) == preWarmed
     }
     
     private func assertValidHybridStart(type: SentryAppStartType) {
diff --git a/Tests/SentryTests/Protocol/TestData.swift b/Tests/SentryTests/Protocol/TestData.swift
index bd7641355df..f200769ebcf 100644
--- a/Tests/SentryTests/Protocol/TestData.swift
+++ b/Tests/SentryTests/Protocol/TestData.swift
@@ -328,9 +328,10 @@ class TestData {
         let appStartDuration = 0.5
         let main = appStartTimestamp.addingTimeInterval(0.15)
         let runtimeInit = appStartTimestamp.addingTimeInterval(0.05)
-        let didFinishLaunching = appStartTimestamp.addingTimeInterval(0.3)
+        let sdkStart = appStartTimestamp.addingTimeInterval(0.1)
+        let didFinishLaunching = appStartTimestamp.addingTimeInterval(0.2)
         
-        return SentryAppStartMeasurement(type: type, isPreWarmed: false, appStartTimestamp: appStartTimestamp, duration: appStartDuration, runtimeInitTimestamp: runtimeInit, moduleInitializationTimestamp: main, didFinishLaunchingTimestamp: didFinishLaunching)
+        return SentryAppStartMeasurement(type: type, isPreWarmed: false, appStartTimestamp: appStartTimestamp, duration: appStartDuration, runtimeInitTimestamp: runtimeInit, moduleInitializationTimestamp: main, sdkStartTimestamp: sdkStart, didFinishLaunchingTimestamp: didFinishLaunching)
     }
 
     #endif // os(iOS) || os(tvOS) || targetEnvironment(macCatalyst)
diff --git a/Tests/SentryTests/SentrySDKTests.swift b/Tests/SentryTests/SentrySDKTests.swift
index 37b63addf27..ed7fb639975 100644
--- a/Tests/SentryTests/SentrySDKTests.swift
+++ b/Tests/SentryTests/SentrySDKTests.swift
@@ -1,3 +1,4 @@
+import Nimble
 @testable import Sentry
 import SentryTestUtils
 import XCTest
@@ -504,6 +505,23 @@ class SentrySDKTests: XCTestCase {
         XCTAssertEqual(1, SentrySDK.startInvocations)
     }
     
+    func testSDKStartTimestamp() {
+        let currentDateProvider = TestCurrentDateProvider()
+        SentryDependencyContainer.sharedInstance().dateProvider = currentDateProvider
+        
+        expect(SentrySDK.startTimestamp) == nil
+        
+        SentrySDK.start { options in
+            options.dsn = SentrySDKTests.dsnAsString
+            options.removeAllIntegrations()
+        }
+        
+        expect(SentrySDK.startTimestamp) == currentDateProvider.date()
+        
+        SentrySDK.close()
+        expect(SentrySDK.startTimestamp) == nil
+    }
+    
     func testIsEnabled() {
         XCTAssertFalse(SentrySDK.isEnabled)
         
diff --git a/Tests/SentryTests/Transaction/SentryTracerTests.swift b/Tests/SentryTests/Transaction/SentryTracerTests.swift
index 2ab9f8b2e98..b9d2dbfd456 100644
--- a/Tests/SentryTests/Transaction/SentryTracerTests.swift
+++ b/Tests/SentryTests/Transaction/SentryTracerTests.swift
@@ -78,13 +78,14 @@ class SentryTracerTests: XCTestCase {
             let runtimeInit = appStart.addingTimeInterval(runtimeInitDuration)
             let mainDuration = 0.15
             let main = appStart.addingTimeInterval(mainDuration)
-            let didFinishLaunching = appStart.addingTimeInterval(0.3)
+            let sdkStart = appStart.addingTimeInterval(0.1)
+            let didFinishLaunching = appStart.addingTimeInterval(0.2)
             appStart = preWarmed ? main : appStart
             appStartDuration = preWarmed ? appStartDuration - runtimeInitDuration - mainDuration : appStartDuration
 
             appStartEnd = appStart.addingTimeInterval(appStartDuration)
 
-            return SentryAppStartMeasurement(type: type, isPreWarmed: preWarmed, appStartTimestamp: appStart, duration: appStartDuration, runtimeInitTimestamp: runtimeInit, moduleInitializationTimestamp: main, didFinishLaunchingTimestamp: didFinishLaunching)
+            return SentryAppStartMeasurement(type: type, isPreWarmed: preWarmed, appStartTimestamp: appStart, duration: appStartDuration, runtimeInitTimestamp: runtimeInit, moduleInitializationTimestamp: main, sdkStartTimestamp: sdkStart, didFinishLaunchingTimestamp: didFinishLaunching)
         }
         #endif // os(iOS) || os(tvOS) || targetEnvironment(macCatalyst)
         
@@ -763,6 +764,7 @@ class SentryTracerTests: XCTestCase {
             duration: 0.5,
             runtimeInitTimestamp: fixture.currentDateProvider.date(),
             moduleInitializationTimestamp: fixture.currentDateProvider.date(),
+            sdkStartTimestamp: fixture.currentDateProvider.date(),
             didFinishLaunchingTimestamp: fixture.currentDateProvider.date()
         ))
         
@@ -1188,7 +1190,7 @@ class SentryTracerTests: XCTestCase {
     #if os(iOS) || os(tvOS) || targetEnvironment(macCatalyst)
     private func assertAppStartsSpanAdded(transaction: Transaction, startType: String, operation: String, appStartMeasurement: SentryAppStartMeasurement) {
         let spans: [SentrySpan]? = Dynamic(transaction).spans
-        XCTAssertEqual(5, spans?.count)
+        expect(spans?.count) == 6
         
         let appLaunchSpan = spans?.first { span in
             span.spanDescription == startType
@@ -1214,7 +1216,8 @@ class SentryTracerTests: XCTestCase {
         
         assertSpan("Pre Runtime Init", appStartMeasurement.appStartTimestamp, appStartMeasurement.runtimeInitTimestamp)
         assertSpan("Runtime Init to Pre Main Initializers", appStartMeasurement.runtimeInitTimestamp, appStartMeasurement.moduleInitializationTimestamp)
-        assertSpan("UIKit and Application Init", appStartMeasurement.moduleInitializationTimestamp, appStartMeasurement.didFinishLaunchingTimestamp)
+        assertSpan("UIKit Init", appStartMeasurement.moduleInitializationTimestamp, appStartMeasurement.sdkStartTimestamp)
+        assertSpan("Application Init", appStartMeasurement.sdkStartTimestamp, appStartMeasurement.didFinishLaunchingTimestamp)
         assertSpan("Initial Frame Render", appStartMeasurement.didFinishLaunchingTimestamp, fixture.appStartEnd)
     }
 
@@ -1230,7 +1233,7 @@ class SentryTracerTests: XCTestCase {
 
     private func assertPreWarmedAppStartsSpanAdded(transaction: Transaction, startType: String, operation: String, appStartMeasurement: SentryAppStartMeasurement) {
             let spans: [SentrySpan]? = Dynamic(transaction).spans
-            XCTAssertEqual(3, spans?.count)
+            expect(spans?.count) == 4
 
             let appLaunchSpan = spans?.first { span in
                 span.spanDescription == startType
@@ -1252,7 +1255,8 @@ class SentryTracerTests: XCTestCase {
                 XCTAssertEqual(timestamp, span?.timestamp)
             }
 
-            assertSpan("UIKit and Application Init", appStartMeasurement.moduleInitializationTimestamp, appStartMeasurement.didFinishLaunchingTimestamp)
+            assertSpan("UIKit Init", appStartMeasurement.moduleInitializationTimestamp, appStartMeasurement.sdkStartTimestamp)
+            assertSpan("Application Init", appStartMeasurement.sdkStartTimestamp, appStartMeasurement.didFinishLaunchingTimestamp)
             assertSpan("Initial Frame Render", appStartMeasurement.didFinishLaunchingTimestamp, fixture.appStartEnd)
         }