diff --git a/packages/replay-internal/src/coreHandlers/performanceObserver.ts b/packages/replay-internal/src/coreHandlers/performanceObserver.ts
index e57369ec7256..47367604085c 100644
--- a/packages/replay-internal/src/coreHandlers/performanceObserver.ts
+++ b/packages/replay-internal/src/coreHandlers/performanceObserver.ts
@@ -9,6 +9,7 @@ import {
   getCumulativeLayoutShift,
   getInteractionToNextPaint,
   getLargestContentfulPaint,
+  rememberEntryTimeOrigin,
   webVitalHandler,
 } from '../util/createPerformanceEntries';
 
@@ -20,6 +21,9 @@ export function setupPerformanceObserver(replay: ReplayContainer): () => void {
   function addPerformanceEntry(entry: PerformanceEntry): void {
     // It is possible for entries to come up multiple times
     if (!replay.performanceEntries.includes(entry)) {
+      // Entries are converted to wall clock time on flush, which can be long after this point, so the time origin that
+      // is currently in effect has to be captured now.
+      rememberEntryTimeOrigin(entry);
       replay.performanceEntries.push(entry);
     }
   }
diff --git a/packages/replay-internal/src/util/createPerformanceEntries.ts b/packages/replay-internal/src/util/createPerformanceEntries.ts
index 2f4e45e9b600..8841a02b1f64 100644
--- a/packages/replay-internal/src/util/createPerformanceEntries.ts
+++ b/packages/replay-internal/src/util/createPerformanceEntries.ts
@@ -16,7 +16,7 @@ import type {
 // Map entryType -> function to normalize data for event
 const ENTRY_TYPES: Record<
   string,
-  (entry: AllPerformanceEntry) => null | ReplayPerformanceEntry<AllPerformanceEntryData>
+  (entry: AllPerformanceEntry, timeOrigin: number) => null | ReplayPerformanceEntry<AllPerformanceEntryData>
 > = {
   // @ts-expect-error TODO: entry type does not fit the create* functions entry type
   resource: createResourceEntry,
@@ -68,6 +68,26 @@ export function webVitalHandler(
   return ({ metric }) => void replay.replayPerformanceEntries.push(getter(metric));
 }
 
+/**
+ * The time origin that was in effect when an entry was observed.
+ *
+ * Entries are buffered raw and only converted to wall clock time on flush, which can be minutes later (and across a
+ * clock drift correction) for a long-running session. Converting them against the origin that was in effect when they
+ * were observed keeps their timestamps correct, whereas the origin at flush time would retroactively shift every
+ * buffered entry by the drift.
+ */
+const ENTRY_TIME_ORIGINS = new WeakMap<AllPerformanceEntry, number>();
+
+/**
+ * Records the current time origin for an observed performance entry, so it can be converted to wall clock time later.
+ */
+export function rememberEntryTimeOrigin(entry: AllPerformanceEntry): void {
+  const timeOrigin = correctedPerformanceTimeOrigin();
+  if (timeOrigin !== undefined) {
+    ENTRY_TIME_ORIGINS.set(entry, timeOrigin);
+  }
+}
+
 /**
  * Create replay performance entries from the browser performance entries.
  */
@@ -83,19 +103,24 @@ function createPerformanceEntry(entry: AllPerformanceEntry): ReplayPerformanceEn
     return null;
   }
 
-  return entryType(entry);
+  return entryType(entry, getEntryTimeOrigin(entry));
+}
+
+function getEntryTimeOrigin(entry: AllPerformanceEntry): number {
+  // The stamp is missing for entries that were not routed through `rememberEntryTimeOrigin` (e.g. web vitals, which
+  // convert eagerly). correctedPerformanceTimeOrigin can be undefined if `performance` or `performance.now` doesn't
+  // exist, but this is already checked by this integration.
+  return ENTRY_TIME_ORIGINS.get(entry) ?? correctedPerformanceTimeOrigin() ?? WINDOW.performance.timeOrigin;
 }
 
-function getAbsoluteTime(time: number): number {
-  // correctedPerformanceTimeOrigin can be undefined if `performance` or
-  // `performance.now` doesn't exist, but this is already checked by this integration
-  return ((correctedPerformanceTimeOrigin() || WINDOW.performance.timeOrigin) + time) / 1000;
+function getAbsoluteTime(time: number, timeOrigin: number): number {
+  return (timeOrigin + time) / 1000;
 }
 
-function createPaintEntry(entry: PerformancePaintTiming): ReplayPerformanceEntry<PaintData> {
+function createPaintEntry(entry: PerformancePaintTiming, timeOrigin: number): ReplayPerformanceEntry<PaintData> {
   const { duration, entryType, name, startTime } = entry;
 
-  const start = getAbsoluteTime(startTime);
+  const start = getAbsoluteTime(startTime, timeOrigin);
   return {
     type: entryType,
     name,
@@ -105,7 +130,10 @@ function createPaintEntry(entry: PerformancePaintTiming): ReplayPerformanceEntry
   };
 }
 
-function createNavigationEntry(entry: PerformanceNavigationTiming): ReplayPerformanceEntry<NavigationData> | null {
+function createNavigationEntry(
+  entry: PerformanceNavigationTiming,
+  timeOrigin: number,
+): ReplayPerformanceEntry<NavigationData> | null {
   const {
     entryType,
     name,
@@ -131,8 +159,8 @@ function createNavigationEntry(entry: PerformanceNavigationTiming): ReplayPerfor
 
   return {
     type: `${entryType}.${type}`,
-    start: getAbsoluteTime(startTime),
-    end: getAbsoluteTime(domComplete),
+    start: getAbsoluteTime(startTime, timeOrigin),
+    end: getAbsoluteTime(domComplete, timeOrigin),
     name,
     data: {
       size: transferSize,
@@ -152,6 +180,7 @@ function createNavigationEntry(entry: PerformanceNavigationTiming): ReplayPerfor
 
 function createResourceEntry(
   entry: ExperimentalPerformanceResourceTiming,
+  timeOrigin: number,
 ): ReplayPerformanceEntry<ResourceData> | null {
   const {
     entryType,
@@ -172,8 +201,8 @@ function createResourceEntry(
 
   return {
     type: `${entryType}.${initiatorType}`,
-    start: getAbsoluteTime(startTime),
-    end: getAbsoluteTime(responseEnd),
+    start: getAbsoluteTime(startTime, timeOrigin),
+    end: getAbsoluteTime(responseEnd, timeOrigin),
     name,
     data: {
       size: transferSize,
@@ -245,7 +274,8 @@ function getWebVital(
   const value = metric.value;
   const rating = metric.rating;
 
-  const end = getAbsoluteTime(value);
+  // Web vitals are converted as they are reported rather than buffered raw, so the current origin is the right one.
+  const end = getAbsoluteTime(value, correctedPerformanceTimeOrigin() ?? WINDOW.performance.timeOrigin);
 
   return {
     type: 'web-vital',
diff --git a/packages/replay-internal/test/unit/util/createPerformanceEntry.test.ts b/packages/replay-internal/test/unit/util/createPerformanceEntry.test.ts
index c87d18bff325..992fa99e79f4 100644
--- a/packages/replay-internal/test/unit/util/createPerformanceEntry.test.ts
+++ b/packages/replay-internal/test/unit/util/createPerformanceEntry.test.ts
@@ -1,4 +1,5 @@
 import '../../utils/mock-internal-setTimeout';
+import { correctedPerformanceTimeOrigin } from '@sentry/core';
 import { afterAll, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
 import { WINDOW } from '../../../src/constants';
 import {
@@ -6,12 +7,13 @@ import {
   getCumulativeLayoutShift,
   getInteractionToNextPaint,
   getLargestContentfulPaint,
+  rememberEntryTimeOrigin,
 } from '../../../src/util/createPerformanceEntries';
 import { PerformanceEntryNavigation } from '../../fixtures/performanceEntry/navigation';
 
 vi.mock('@sentry/core', async () => ({
   ...(await vi.importActual('@sentry/core')),
-  browserPerformanceTimeOrigin: () => new Date('2023-01-01').getTime(),
+  correctedPerformanceTimeOrigin: vi.fn(() => new Date('2023-01-01').getTime()),
 }));
 
 describe('Unit | util | createPerformanceEntries', () => {
@@ -21,6 +23,8 @@ describe('Unit | util | createPerformanceEntries', () => {
   });
 
   beforeEach(function () {
+    vi.mocked(correctedPerformanceTimeOrigin).mockReturnValue(new Date('2023-01-01').getTime());
+
     if (!WINDOW.performance.getEntriesByType) {
       WINDOW.performance.getEntriesByType = vi.fn((type: string) => {
         if (type === 'navigation') {
@@ -67,6 +71,64 @@ describe('Unit | util | createPerformanceEntries', () => {
     expect(createPerformanceEntries([data])).toEqual([]);
   });
 
+  describe('time origin stamping', () => {
+    const TIME_ORIGIN = new Date('2023-01-01').getTime();
+    // A sleep long enough for `timestampInSeconds` to re-derive its time origin.
+    const DRIFT_MS = 360_000;
+
+    function resourceEntry(): PerformanceEntry {
+      return {
+        name: 'https://example.com/script.js',
+        entryType: 'resource',
+        startTime: 1_000,
+        duration: 100,
+        initiatorType: 'script',
+        responseEnd: 1_100,
+        transferSize: 0,
+        encodedBodySize: 0,
+        decodedBodySize: 0,
+      } as unknown as PerformanceEntry;
+    }
+
+    it('converts a stamped entry against the origin from when it was observed', () => {
+      const entry = resourceEntry();
+
+      rememberEntryTimeOrigin(entry);
+
+      // The origin is corrected after the entry was observed but before it is flushed.
+      vi.mocked(correctedPerformanceTimeOrigin).mockReturnValue(TIME_ORIGIN + DRIFT_MS);
+
+      const [replayEntry] = createPerformanceEntries([entry]);
+
+      expect(replayEntry?.start).toBe((TIME_ORIGIN + 1_000) / 1000);
+      expect(replayEntry?.end).toBe((TIME_ORIGIN + 1_100) / 1000);
+    });
+
+    it('falls back to the current origin for an entry that was never stamped', () => {
+      vi.mocked(correctedPerformanceTimeOrigin).mockReturnValue(TIME_ORIGIN + DRIFT_MS);
+
+      const [replayEntry] = createPerformanceEntries([resourceEntry()]);
+
+      expect(replayEntry?.start).toBe((TIME_ORIGIN + DRIFT_MS + 1_000) / 1000);
+    });
+
+    it('stamps each entry with the origin in effect when it was observed', () => {
+      const early = resourceEntry();
+      rememberEntryTimeOrigin(early);
+
+      vi.mocked(correctedPerformanceTimeOrigin).mockReturnValue(TIME_ORIGIN + DRIFT_MS);
+      const late = resourceEntry();
+      rememberEntryTimeOrigin(late);
+
+      const [earlyEntry, lateEntry] = createPerformanceEntries([early, late]);
+
+      // Both entries carry the same monotonic `startTime`, so a shared origin would collapse them onto the same
+      // wall clock time even though they were observed on either side of a correction.
+      expect(earlyEntry?.start).toBe((TIME_ORIGIN + 1_000) / 1000);
+      expect(lateEntry?.start).toBe((TIME_ORIGIN + DRIFT_MS + 1_000) / 1000);
+    });
+  });
+
   describe('getLargestContentfulPaint', () => {
     it('works with an LCP metric', async () => {
       const metric = {