diff --git a/packages/react-native/src/private/webapis/performance/Performance.js b/packages/react-native/src/private/webapis/performance/Performance.js
index dbadef33aa4..80defff2554 100644
--- a/packages/react-native/src/private/webapis/performance/Performance.js
+++ b/packages/react-native/src/private/webapis/performance/Performance.js
@@ -10,12 +10,12 @@
 
 // flowlint unsafe-getters-setters:off
 
-import type {HighResTimeStamp, PerformanceEntryType} from './PerformanceEntry';
-import type {PerformanceEntryList} from './PerformanceObserver';
 import type {
-  PerformanceMarkOptions,
-  PerformanceMeasureOptions,
-} from './UserTiming';
+  DOMHighResTimeStamp,
+  PerformanceEntryType,
+} from './PerformanceEntry';
+import type {PerformanceEntryList} from './PerformanceObserver';
+import type {DetailType, PerformanceMarkOptions} from './UserTiming';
 
 import warnOnce from '../../../../Libraries/Utilities/warnOnce';
 import EventCounts from './EventCounts';
@@ -37,7 +37,7 @@ declare var global: {
   +nativePerformanceNow?: ?() => number,
 };
 
-const getCurrentTimeStamp: () => HighResTimeStamp =
+const getCurrentTimeStamp: () => DOMHighResTimeStamp =
   NativePerformance?.now ?? global.nativePerformanceNow ?? (() => Date.now());
 
 // We want some of the performance entry types to be always logged,
@@ -58,6 +58,13 @@ function warnNoNativePerformance() {
   );
 }
 
+export type PerformanceMeasureOptions = {
+  detail?: DetailType,
+  start?: DOMHighResTimeStamp,
+  duration?: DOMHighResTimeStamp,
+  end?: DOMHighResTimeStamp,
+};
+
 /**
  * Partial implementation of the Performance interface for RN,
  * corresponding to the standard in
@@ -195,7 +202,13 @@ export default class Performance {
       duration = options.duration ?? duration;
     }
 
-    const measure = new PerformanceMeasure(measureName, options);
+    const measure = new PerformanceMeasure(measureName, {
+      // FIXME(T196011255): this is incorrect, as we're only assigning the
+      // start/end if they're specified as a number, but not if they're
+      // specified as previous mark names.
+      startTime,
+      duration,
+    });
 
     if (NativePerformance?.measure) {
       NativePerformance.measure(
@@ -229,7 +242,7 @@ export default class Performance {
    * Returns a double, measured in milliseconds.
    * https://developer.mozilla.org/en-US/docs/Web/API/Performance/now
    */
-  now(): HighResTimeStamp {
+  now(): DOMHighResTimeStamp {
     return getCurrentTimeStamp();
   }
 
diff --git a/packages/react-native/src/private/webapis/performance/PerformanceEntry.js b/packages/react-native/src/private/webapis/performance/PerformanceEntry.js
index 62c0b022665..4eca7229847 100644
--- a/packages/react-native/src/private/webapis/performance/PerformanceEntry.js
+++ b/packages/react-native/src/private/webapis/performance/PerformanceEntry.js
@@ -8,14 +8,16 @@
  * @flow strict
  */
 
-export type HighResTimeStamp = number;
+// flowlint unsafe-getters-setters:off
+
+export type DOMHighResTimeStamp = number;
 export type PerformanceEntryType = 'mark' | 'measure' | 'event' | 'longtask';
 
 export type PerformanceEntryJSON = {
   name: string,
   entryType: PerformanceEntryType,
-  startTime: HighResTimeStamp,
-  duration: HighResTimeStamp,
+  startTime: DOMHighResTimeStamp,
+  duration: DOMHighResTimeStamp,
   ...
 };
 
@@ -25,29 +27,45 @@ export const ALWAYS_LOGGED_ENTRY_TYPES: $ReadOnlyArray<PerformanceEntryType> = [
 ];
 
 export class PerformanceEntry {
-  name: string;
-  entryType: PerformanceEntryType;
-  startTime: HighResTimeStamp;
-  duration: HighResTimeStamp;
+  #name: string;
+  #entryType: PerformanceEntryType;
+  #startTime: DOMHighResTimeStamp;
+  #duration: DOMHighResTimeStamp;
 
   constructor(init: {
     name: string,
     entryType: PerformanceEntryType,
-    startTime: HighResTimeStamp,
-    duration: HighResTimeStamp,
+    startTime: DOMHighResTimeStamp,
+    duration: DOMHighResTimeStamp,
   }) {
-    this.name = init.name;
-    this.entryType = init.entryType;
-    this.startTime = init.startTime;
-    this.duration = init.duration;
+    this.#name = init.name;
+    this.#entryType = init.entryType;
+    this.#startTime = init.startTime;
+    this.#duration = init.duration;
+  }
+
+  get name(): string {
+    return this.#name;
+  }
+
+  get entryType(): PerformanceEntryType {
+    return this.#entryType;
+  }
+
+  get startTime(): DOMHighResTimeStamp {
+    return this.#startTime;
+  }
+
+  get duration(): DOMHighResTimeStamp {
+    return this.#duration;
   }
 
   toJSON(): PerformanceEntryJSON {
     return {
-      name: this.name,
-      entryType: this.entryType,
-      startTime: this.startTime,
-      duration: this.duration,
+      name: this.#name,
+      entryType: this.#entryType,
+      startTime: this.#startTime,
+      duration: this.#duration,
     };
   }
 }
diff --git a/packages/react-native/src/private/webapis/performance/PerformanceEventTiming.js b/packages/react-native/src/private/webapis/performance/PerformanceEventTiming.js
index 9f2fa2bfcb8..3c806c4700a 100644
--- a/packages/react-native/src/private/webapis/performance/PerformanceEventTiming.js
+++ b/packages/react-native/src/private/webapis/performance/PerformanceEventTiming.js
@@ -8,29 +8,34 @@
  * @flow strict
  */
 
-import type {HighResTimeStamp, PerformanceEntryJSON} from './PerformanceEntry';
+// flowlint unsafe-getters-setters:off
+
+import type {
+  DOMHighResTimeStamp,
+  PerformanceEntryJSON,
+} from './PerformanceEntry';
 
 import {PerformanceEntry} from './PerformanceEntry';
 
 export type PerformanceEventTimingJSON = {
   ...PerformanceEntryJSON,
-  processingStart: HighResTimeStamp,
-  processingEnd: HighResTimeStamp,
+  processingStart: DOMHighResTimeStamp,
+  processingEnd: DOMHighResTimeStamp,
   interactionId: number,
   ...
 };
 
 export default class PerformanceEventTiming extends PerformanceEntry {
-  processingStart: HighResTimeStamp;
-  processingEnd: HighResTimeStamp;
-  interactionId: number;
+  #processingStart: DOMHighResTimeStamp;
+  #processingEnd: DOMHighResTimeStamp;
+  #interactionId: number;
 
   constructor(init: {
     name: string,
-    startTime?: HighResTimeStamp,
-    duration?: HighResTimeStamp,
-    processingStart?: HighResTimeStamp,
-    processingEnd?: HighResTimeStamp,
+    startTime?: DOMHighResTimeStamp,
+    duration?: DOMHighResTimeStamp,
+    processingStart?: DOMHighResTimeStamp,
+    processingEnd?: DOMHighResTimeStamp,
     interactionId?: number,
   }) {
     super({
@@ -39,17 +44,29 @@ export default class PerformanceEventTiming extends PerformanceEntry {
       startTime: init.startTime ?? 0,
       duration: init.duration ?? 0,
     });
-    this.processingStart = init.processingStart ?? 0;
-    this.processingEnd = init.processingEnd ?? 0;
-    this.interactionId = init.interactionId ?? 0;
+    this.#processingStart = init.processingStart ?? 0;
+    this.#processingEnd = init.processingEnd ?? 0;
+    this.#interactionId = init.interactionId ?? 0;
+  }
+
+  get processingStart(): DOMHighResTimeStamp {
+    return this.#processingStart;
+  }
+
+  get processingEnd(): DOMHighResTimeStamp {
+    return this.#processingEnd;
+  }
+
+  get interactionId(): number {
+    return this.#interactionId;
   }
 
   toJSON(): PerformanceEventTimingJSON {
     return {
       ...super.toJSON(),
-      processingStart: this.processingStart,
-      processingEnd: this.processingEnd,
-      interactionId: this.interactionId,
+      processingStart: this.#processingStart,
+      processingEnd: this.#processingEnd,
+      interactionId: this.#interactionId,
     };
   }
 }
diff --git a/packages/react-native/src/private/webapis/performance/PerformanceObserver.js b/packages/react-native/src/private/webapis/performance/PerformanceObserver.js
index 440d0b55cf8..4a3984874ea 100644
--- a/packages/react-native/src/private/webapis/performance/PerformanceObserver.js
+++ b/packages/react-native/src/private/webapis/performance/PerformanceObserver.js
@@ -8,7 +8,10 @@
  * @flow strict
  */
 
-import type {HighResTimeStamp, PerformanceEntryType} from './PerformanceEntry';
+import type {
+  DOMHighResTimeStamp,
+  PerformanceEntryType,
+} from './PerformanceEntry';
 
 import warnOnce from '../../../../Libraries/Utilities/warnOnce';
 import {PerformanceEntry} from './PerformanceEntry';
@@ -66,7 +69,7 @@ export type PerformanceObserverInit =
     }
   | {
       type: PerformanceEntryType,
-      durationThreshold?: HighResTimeStamp,
+      durationThreshold?: DOMHighResTimeStamp,
     };
 
 type PerformanceObserverConfig = {|
diff --git a/packages/react-native/src/private/webapis/performance/RawPerformanceEntry.js b/packages/react-native/src/private/webapis/performance/RawPerformanceEntry.js
index 861a0fd6580..843886f19a3 100644
--- a/packages/react-native/src/private/webapis/performance/RawPerformanceEntry.js
+++ b/packages/react-native/src/private/webapis/performance/RawPerformanceEntry.js
@@ -16,6 +16,7 @@ import type {
 
 import {PerformanceEntry} from './PerformanceEntry';
 import PerformanceEventTiming from './PerformanceEventTiming';
+import {PerformanceMark, PerformanceMeasure} from './UserTiming';
 
 export const RawPerformanceEntryTypeValues = {
   MARK: 1,
@@ -36,6 +37,15 @@ export function rawToPerformanceEntry(
       processingEnd: entry.processingEnd,
       interactionId: entry.interactionId,
     });
+  } else if (entry.entryType === RawPerformanceEntryTypeValues.MARK) {
+    return new PerformanceMark(entry.name, {
+      startTime: entry.startTime,
+    });
+  } else if (entry.entryType === RawPerformanceEntryTypeValues.MEASURE) {
+    return new PerformanceMeasure(entry.name, {
+      startTime: entry.startTime,
+      duration: entry.duration,
+    });
   } else {
     return new PerformanceEntry({
       name: entry.name,
diff --git a/packages/react-native/src/private/webapis/performance/UserTiming.js b/packages/react-native/src/private/webapis/performance/UserTiming.js
index 2380e71731e..f3d7865a5cd 100644
--- a/packages/react-native/src/private/webapis/performance/UserTiming.js
+++ b/packages/react-native/src/private/webapis/performance/UserTiming.js
@@ -8,24 +8,25 @@
  * @flow strict
  */
 
-import type {HighResTimeStamp} from './PerformanceEntry';
+// flowlint unsafe-getters-setters:off
+
+import type {DOMHighResTimeStamp} from './PerformanceEntry';
 
 import {PerformanceEntry} from './PerformanceEntry';
 
-type DetailType = mixed;
+export type DetailType = mixed;
 
 export type PerformanceMarkOptions = {
   detail?: DetailType,
-  startTime?: HighResTimeStamp,
+  startTime?: DOMHighResTimeStamp,
 };
 
-export type TimeStampOrName = HighResTimeStamp | string;
+export type TimeStampOrName = DOMHighResTimeStamp | string;
 
-export type PerformanceMeasureOptions = {
+export type PerformanceMeasureInit = {
   detail?: DetailType,
-  start?: TimeStampOrName,
-  end?: TimeStampOrName,
-  duration?: HighResTimeStamp,
+  startTime?: DOMHighResTimeStamp,
+  duration?: DOMHighResTimeStamp,
 };
 
 export class PerformanceMark extends PerformanceEntry {
@@ -46,18 +47,22 @@ export class PerformanceMark extends PerformanceEntry {
 }
 
 export class PerformanceMeasure extends PerformanceEntry {
-  detail: DetailType;
+  #detail: DetailType;
 
-  constructor(measureName: string, measureOptions?: PerformanceMeasureOptions) {
+  constructor(measureName: string, measureOptions?: PerformanceMeasureInit) {
     super({
       name: measureName,
       entryType: 'measure',
-      startTime: 0,
+      startTime: measureOptions?.startTime ?? 0,
       duration: measureOptions?.duration ?? 0,
     });
 
     if (measureOptions) {
-      this.detail = measureOptions.detail;
+      this.#detail = measureOptions.detail;
     }
   }
+
+  get detail(): DetailType {
+    return this.#detail;
+  }
 }