diff --git a/packages/rum-core/src/browser/performanceCollection.ts b/packages/rum-core/src/browser/performanceCollection.ts
index 74314326de..adc4a2ce5d 100644
--- a/packages/rum-core/src/browser/performanceCollection.ts
+++ b/packages/rum-core/src/browser/performanceCollection.ts
@@ -86,7 +86,9 @@ export interface RumFirstInputTiming {
   entryType: 'first-input'
   startTime: RelativeTime
   processingStart: RelativeTime
+  duration: Duration
   target?: Node
+  interactionId?: number
 }
 
 export interface RumPerformanceEventTiming {
@@ -264,6 +266,7 @@ function retrieveFirstInputTiming(configuration: RumConfiguration, callback: (ti
         entryType: 'first-input',
         processingStart: relativeNow(),
         startTime: evt.timeStamp as RelativeTime,
+        duration: 0 as Duration, // arbitrary value to avoid nullable duration and simplify INP logic
       }
 
       if (evt.type === DOM_EVENT.POINTER_DOWN) {
diff --git a/packages/rum-core/src/domain/rumEventsCollection/view/trackInitialViewTimings.spec.ts b/packages/rum-core/src/domain/rumEventsCollection/view/trackInitialViewTimings.spec.ts
index f300f68772..f38d4d57f8 100644
--- a/packages/rum-core/src/domain/rumEventsCollection/view/trackInitialViewTimings.spec.ts
+++ b/packages/rum-core/src/domain/rumEventsCollection/view/trackInitialViewTimings.spec.ts
@@ -50,6 +50,7 @@ const FAKE_FIRST_INPUT_ENTRY: RumFirstInputTiming = {
   processingStart: 1100 as RelativeTime,
   startTime: 1000 as RelativeTime,
   target: document.createElement('button'),
+  duration: 0 as Duration,
 }
 
 describe('trackInitialViewTimings', () => {
@@ -325,6 +326,7 @@ describe('firstInputTimings', () => {
         entryType: 'first-input' as const,
         processingStart: 900 as RelativeTime,
         startTime: 1000 as RelativeTime,
+        duration: 0 as Duration,
       },
     ])
 
diff --git a/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.spec.ts b/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.spec.ts
index 46afe230ec..6e8388b86b 100644
--- a/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.spec.ts
+++ b/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.spec.ts
@@ -1,4 +1,4 @@
-import type { Duration } from '@datadog/browser-core'
+import type { Duration, RelativeTime } from '@datadog/browser-core'
 import {
   ExperimentalFeature,
   addExperimentalFeatures,
@@ -7,7 +7,11 @@ import {
 } from '@datadog/browser-core'
 import type { TestSetupBuilder } from '../../../../test'
 import { setup } from '../../../../test'
-import type { BrowserWindow, RumPerformanceEventTiming } from '../../../browser/performanceCollection'
+import type {
+  BrowserWindow,
+  RumFirstInputTiming,
+  RumPerformanceEventTiming,
+} from '../../../browser/performanceCollection'
 import { ViewLoadingType } from '../../../rawRumEvent.types'
 import type { LifeCycle } from '../../lifeCycle'
 import { LifeCycleEventType } from '../../lifeCycle'
@@ -24,7 +28,11 @@ describe('trackInteractionToNextPaint', () => {
 
   function newInteraction(
     lifeCycle: LifeCycle,
-    { interactionId, duration = 40 as Duration, entryType = 'event' }: Partial<RumPerformanceEventTiming>
+    {
+      interactionId,
+      duration = 40 as Duration,
+      entryType = 'event',
+    }: Partial<RumPerformanceEventTiming | RumFirstInputTiming>
   ) {
     if (interactionId) {
       interactionCountStub.incrementInteractionCount()
@@ -32,6 +40,7 @@ describe('trackInteractionToNextPaint', () => {
     lifeCycle.notify(LifeCycleEventType.PERFORMANCE_ENTRIES_COLLECTED, [
       {
         entryType,
+        processingStart: relativeNow(),
         startTime: relativeNow(),
         duration,
         interactionId,
@@ -92,6 +101,15 @@ describe('trackInteractionToNextPaint', () => {
       interactionCountStub.setInteractionCount(1 as Duration) // assumes an interaction happened but no PERFORMANCE_ENTRIES_COLLECTED have been triggered
       expect(getInteractionToNextPaint()).toEqual(0 as Duration)
     })
+
+    it('should take first-input entry into account', () => {
+      const { lifeCycle } = setupBuilder.build()
+      newInteraction(lifeCycle, {
+        interactionId: 1,
+        entryType: 'first-input',
+      })
+      expect(getInteractionToNextPaint()).toEqual(40 as Duration)
+    })
   })
 
   describe('if feature flag disabled', () => {
diff --git a/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.ts b/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.ts
index b33b4c5ce2..8d935c1863 100644
--- a/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.ts
+++ b/packages/rum-core/src/domain/rumEventsCollection/view/trackInteractionToNextPaint.ts
@@ -1,5 +1,6 @@
 import { type Duration, noop, isExperimentalFeatureEnabled, ExperimentalFeature } from '@datadog/browser-core'
-import { supportPerformanceTimingEvent, type RumPerformanceEventTiming } from '../../../browser/performanceCollection'
+import { supportPerformanceTimingEvent } from '../../../browser/performanceCollection'
+import type { RumFirstInputTiming, RumPerformanceEventTiming } from '../../../browser/performanceCollection'
 import { LifeCycleEventType, type LifeCycle } from '../../lifeCycle'
 import { ViewLoadingType } from '../../../rawRumEvent.types'
 import { getInteractionCount, initInteractionCountPolyfill } from './interactionCountPolyfill'
@@ -30,7 +31,7 @@ export function trackInteractionToNextPaint(viewLoadingType: ViewLoadingType, li
 
   const { unsubscribe: stop } = lifeCycle.subscribe(LifeCycleEventType.PERFORMANCE_ENTRIES_COLLECTED, (entries) => {
     for (const entry of entries) {
-      if (entry.entryType === 'event' && entry.interactionId) {
+      if ((entry.entryType === 'event' || entry.entryType === 'first-input') && entry.interactionId) {
         longestInteractions.process(entry)
       }
     }
@@ -56,7 +57,7 @@ export function trackInteractionToNextPaint(viewLoadingType: ViewLoadingType, li
 }
 
 function trackLongestInteractions(getViewInteractionCount: () => number) {
-  const longestInteractions: RumPerformanceEventTiming[] = []
+  const longestInteractions: Array<RumPerformanceEventTiming | RumFirstInputTiming> = []
 
   function sortAndTrimLongestInteractions() {
     longestInteractions.sort((a, b) => b.duration - a.duration).splice(MAX_INTERACTION_ENTRIES)
@@ -68,7 +69,7 @@ function trackLongestInteractions(getViewInteractionCount: () => number) {
      * - if its duration is long enough, add the performance entry to the list of worst interactions
      * - if an entry with the same interaction id exists and its duration is lower than the new one, then replace it in the list of worst interactions
      */
-    process(entry: RumPerformanceEventTiming) {
+    process(entry: RumPerformanceEventTiming | RumFirstInputTiming) {
       const interactionIndex = longestInteractions.findIndex(
         (interaction) => entry.interactionId === interaction.interactionId
       )