diff --git a/services/apps/script_executor_worker/package.json b/services/apps/script_executor_worker/package.json
index c020c48e42..fec64ac062 100644
--- a/services/apps/script_executor_worker/package.json
+++ b/services/apps/script_executor_worker/package.json
@@ -7,6 +7,7 @@
     "dev:local": "nodemon --watch src --watch ../../libs --ext ts --exec pnpm run start:debug:local",
     "dev": "nodemon --watch src --watch ../../libs --ext ts --exec pnpm run start:debug",
     "cleanup-fork-activities": "npx tsx src/bin/cleanup-fork-activities-and-maintainers.ts",
+    "fix-activity-relations-memberId": "npx tsx src/bin/fix-activityRelations-memberId.ts",
     "lint": "npx eslint --ext .ts src --max-warnings=0",
     "format": "npx prettier --write \"src/**/*.ts\"",
     "format-check": "npx prettier --check .",
diff --git a/services/apps/script_executor_worker/src/activities.ts b/services/apps/script_executor_worker/src/activities.ts
index f0b9f96810..f43ebb75e7 100644
--- a/services/apps/script_executor_worker/src/activities.ts
+++ b/services/apps/script_executor_worker/src/activities.ts
@@ -27,6 +27,11 @@ import {
   findMemberIdentitiesGroupedByPlatform,
   findMemberMergeActions,
 } from './activities/dissect-member'
+import {
+  findMemberIdByUsernameAndPlatform,
+  findMembersWithWrongActivityRelations,
+  moveActivityRelations,
+} from './activities/fix-activityRelations-memberId'
 import {
   getBotMembersWithOrgAffiliation,
   removeBotMemberOrganization,
@@ -86,4 +91,7 @@ export {
   blockMemberOrganizationAffiliation,
   getOrganizationMembers,
   calculateMemberAffiliations,
+  findMembersWithWrongActivityRelations,
+  findMemberIdByUsernameAndPlatform,
+  moveActivityRelations,
 }
diff --git a/services/apps/script_executor_worker/src/activities/fix-activityRelations-memberId.ts b/services/apps/script_executor_worker/src/activities/fix-activityRelations-memberId.ts
new file mode 100644
index 0000000000..c8aa87fcc2
--- /dev/null
+++ b/services/apps/script_executor_worker/src/activities/fix-activityRelations-memberId.ts
@@ -0,0 +1,64 @@
+import { moveActivityRelationsWithIdentityToAnotherMember, pgpQx } from '@crowd/data-access-layer'
+import { IDbActivityRelation } from '@crowd/data-access-layer/src/activityRelations/types'
+import MemberRepository from '@crowd/data-access-layer/src/old/apps/script_executor_worker/member.repo'
+
+import { svc } from '../main'
+
+export async function findMembersWithWrongActivityRelations(
+  platform: string,
+  batchSize: number,
+): Promise<Partial<IDbActivityRelation>[]> {
+  try {
+    const memberRepo = new MemberRepository(svc.postgres.reader.connection(), svc.log)
+    const records = await memberRepo.findMembersWithIncorrectActivityRelations(platform, batchSize)
+
+    // Deduplicate by (memberId, username, platform)
+    const seen = new Set<string>()
+    const uniqueRecords: Partial<IDbActivityRelation>[] = []
+
+    for (const record of records) {
+      const key = `${record.memberId}:${record.username}:${record.platform}`
+
+      if (!seen.has(key)) {
+        seen.add(key)
+        uniqueRecords.push(record)
+      }
+    }
+
+    return uniqueRecords
+  } catch (error) {
+    svc.log.error(error, 'Error finding activity relations with wrong member id!')
+    throw error
+  }
+}
+
+export async function findMemberIdByUsernameAndPlatform(
+  username: string,
+  platform: string,
+): Promise<string> {
+  try {
+    const memberRepo = new MemberRepository(svc.postgres.reader.connection(), svc.log)
+    return memberRepo.getMemberIdByUsernameAndPlatform(username, platform)
+  } catch (error) {
+    svc.log.error(
+      { error, username, platform },
+      'Error getting member id by username and platform!',
+    )
+    throw error
+  }
+}
+
+export async function moveActivityRelations(
+  fromId: string,
+  toId: string,
+  username: string,
+  platform: string,
+): Promise<void> {
+  try {
+    const qx = pgpQx(svc.postgres.writer.connection())
+    await moveActivityRelationsWithIdentityToAnotherMember(qx, fromId, toId, username, platform)
+  } catch (error) {
+    svc.log.error(error, 'Error fixing activity relations!')
+    throw error
+  }
+}
diff --git a/services/apps/script_executor_worker/src/bin/fix-activityRelations-memberId.ts b/services/apps/script_executor_worker/src/bin/fix-activityRelations-memberId.ts
new file mode 100644
index 0000000000..d3e111ca60
--- /dev/null
+++ b/services/apps/script_executor_worker/src/bin/fix-activityRelations-memberId.ts
@@ -0,0 +1,262 @@
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import { moveActivityRelationsWithIdentityToAnotherMember } from '@crowd/data-access-layer'
+import {
+  READ_DB_CONFIG,
+  WRITE_DB_CONFIG,
+  getDbConnection,
+} from '@crowd/data-access-layer/src/database'
+import { QueryExecutor, pgpQx } from '@crowd/data-access-layer/src/queryExecutor'
+import { getServiceChildLogger } from '@crowd/logging'
+
+import { chunkArray } from '../utils/common'
+
+const log = getServiceChildLogger('fix-activity-relations-memberId-script')
+
+interface IPostgresClient {
+  reader: QueryExecutor
+  writer: QueryExecutor
+}
+
+interface IMemberIdentity {
+  id: string
+  memberId: string
+  username: string
+  platform: string
+}
+
+async function initPostgresClient(): Promise<IPostgresClient> {
+  const reader = await getDbConnection(READ_DB_CONFIG())
+  const writer = await getDbConnection(WRITE_DB_CONFIG())
+  return {
+    reader: pgpQx(reader),
+    writer: pgpQx(writer),
+  }
+}
+
+/**
+ * Get the total number of member verified identities.
+ */
+async function getTotalMemberVerifiedIdentities(qx: QueryExecutor): Promise<number> {
+  const result = await qx.selectOne(
+    `
+    SELECT COUNT(*) FROM "memberIdentities" WHERE type = 'username' AND verified = true;
+    `,
+  )
+
+  return Number(result?.count ?? 0)
+}
+
+/**
+ * Get batch of member identities using cursor-based pagination.
+ * Uses primary key index - very fast.
+ */
+async function getMemberIdentitiesBatch(
+  qx: QueryExecutor,
+  lastId: string | null,
+  batchSize: number,
+): Promise<IMemberIdentity[]> {
+  return qx.select(
+    `
+    SELECT id, "memberId", value as username, platform
+    FROM "memberIdentities"
+    WHERE type = 'username'
+      AND verified = true
+      AND id > $(lastId)
+    ORDER BY id
+    LIMIT $(batchSize);
+    `,
+    { lastId: lastId || '00000000-0000-0000-0000-000000000000', batchSize },
+  )
+}
+
+/**
+ * Get the wrong memberId for this identity (to pass to moveActivityRelations).
+ * Uses ix_activityrelations_platform_username_memberid index - very fast.
+ */
+async function findIncorrectActivityRelationMemberId(
+  qx: QueryExecutor,
+  platform: string,
+  username: string,
+  correctMemberId: string,
+): Promise<string | null> {
+  const result = await qx.selectOneOrNone(
+    `
+    SELECT "memberId"
+    FROM "activityRelations"
+    WHERE platform = $(platform)
+      AND username = $(username)
+      AND "memberId" != $(correctMemberId)
+    LIMIT 1;
+    `,
+    { platform, username, correctMemberId },
+  )
+  return result?.memberId || null
+}
+
+async function findIncorrectObjectActivityRelationMemberId(
+  qx: QueryExecutor,
+  platform: string,
+  objectMemberUsername: string,
+  correctObjectMemberId: string,
+): Promise<string | null> {
+  const result = await qx.selectOneOrNone(
+    `
+    SELECT "objectMemberId"
+    FROM "activityRelations"
+    WHERE platform = $(platform)
+      AND "objectMemberUsername" = $(objectMemberUsername)
+      AND "objectMemberId" != $(correctObjectMemberId)
+    LIMIT 1;
+    `,
+    { platform, objectMemberUsername, correctObjectMemberId },
+  )
+
+  return result?.objectMemberId || null
+}
+
+async function moveActivityRelations(
+  qx: QueryExecutor,
+  fromId: string,
+  toId: string,
+  username: string,
+  platform: string,
+): Promise<void> {
+  await moveActivityRelationsWithIdentityToAnotherMember(qx, fromId, toId, username, platform)
+}
+
+async function main() {
+  const args = Object.fromEntries(
+    process.argv.slice(2).map((arg) => {
+      const [key, val] = arg.split('=')
+      return [key.replace(/^--/, ''), val ?? true]
+    }),
+  )
+
+  const batchSize = Number(args['batch-size'] ?? 5000)
+  const testRun = Boolean(args['test-run'])
+  let lastId: string | null = (args['start-id'] as string | null) ?? null
+
+  log.info('Running script with args', { batchSize, testRun, lastId })
+
+  const { reader: qxReader, writer: qxWriter } = await initPostgresClient()
+
+  let totalProcessed = 0
+  let totalMemberIdFixes = 0
+  let totalObjectMemberIdFixes = 0
+
+  const totalMemberVerifiedIdentities = await getTotalMemberVerifiedIdentities(qxReader)
+
+  let identities = await getMemberIdentitiesBatch(qxReader, lastId, batchSize)
+
+  while (identities.length > 0) {
+    for (const chunk of chunkArray(identities, 50)) {
+      const tasks = chunk.map(async (identity) => {
+        let memberIdFixCount = 0
+        let objectMemberIdFixCount = 0
+
+        // Fix all wrong memberIds for this identity
+        let wrongMemberId = await findIncorrectActivityRelationMemberId(
+          qxReader,
+          identity.platform,
+          identity.username,
+          identity.memberId,
+        )
+
+        while (wrongMemberId) {
+          log.info('Moving activity relations (memberId)', {
+            fromId: wrongMemberId,
+            toId: identity.memberId,
+            username: identity.username,
+            platform: identity.platform,
+          })
+
+          await moveActivityRelations(
+            qxWriter,
+            wrongMemberId,
+            identity.memberId,
+            identity.username,
+            identity.platform,
+          )
+
+          memberIdFixCount++
+
+          // Check again for more wrong memberIds
+          wrongMemberId = await findIncorrectActivityRelationMemberId(
+            qxReader,
+            identity.platform,
+            identity.username,
+            identity.memberId,
+          )
+        }
+
+        // Fix all wrong objectMemberIds for this identity
+        let wrongObjectMemberId = await findIncorrectObjectActivityRelationMemberId(
+          qxReader,
+          identity.platform,
+          identity.username,
+          identity.memberId,
+        )
+
+        while (wrongObjectMemberId) {
+          log.info('Moving activity relations (objectMemberId)', {
+            fromId: wrongObjectMemberId,
+            toId: identity.memberId,
+            username: identity.username,
+            platform: identity.platform,
+          })
+
+          await moveActivityRelations(
+            qxWriter,
+            wrongObjectMemberId,
+            identity.memberId,
+            identity.username,
+            identity.platform,
+          )
+
+          objectMemberIdFixCount++
+
+          // Check again for more wrong objectMemberIds
+          wrongObjectMemberId = await findIncorrectObjectActivityRelationMemberId(
+            qxReader,
+            identity.platform,
+            identity.username,
+            identity.memberId,
+          )
+        }
+
+        return {
+          memberIdFixes: memberIdFixCount,
+          objectMemberIdFixes: objectMemberIdFixCount,
+        }
+      })
+
+      const results = await Promise.all(tasks)
+      for (const result of results) {
+        totalMemberIdFixes += result.memberIdFixes
+        totalObjectMemberIdFixes += result.objectMemberIdFixes
+      }
+    }
+
+    totalProcessed += identities.length
+    lastId = identities[identities.length - 1].id
+
+    log.info(`Progress`, {
+      progress: ((totalProcessed / totalMemberVerifiedIdentities) * 100).toFixed(2) + '%',
+      lastIdentityId: lastId,
+    })
+
+    if (testRun) {
+      log.info('Test run - stopping after first batch')
+      break
+    }
+
+    identities = await getMemberIdentitiesBatch(qxReader, lastId, batchSize)
+  }
+
+  log.info('Script completed', { totalMemberIdFixes, totalObjectMemberIdFixes })
+}
+
+main().catch((error) => {
+  log.error('Unexpected error:', error)
+  process.exit(1)
+})
diff --git a/services/apps/script_executor_worker/src/types.ts b/services/apps/script_executor_worker/src/types.ts
index 8c94682e0c..0783b685a3 100644
--- a/services/apps/script_executor_worker/src/types.ts
+++ b/services/apps/script_executor_worker/src/types.ts
@@ -61,3 +61,7 @@ export interface IBlockOrganizationAffiliationArgs {
   organizationId: string
   offset?: number
 }
+
+export interface IFixActivityRelationsMemberIdArgs extends IScriptBatchTestArgs {
+  currentPlatformIndex?: number
+}
diff --git a/services/apps/script_executor_worker/src/workflows.ts b/services/apps/script_executor_worker/src/workflows.ts
index 5a1cd5468b..02da6cb65d 100644
--- a/services/apps/script_executor_worker/src/workflows.ts
+++ b/services/apps/script_executor_worker/src/workflows.ts
@@ -5,6 +5,7 @@ import { cleanupOrganizations } from './workflows/cleanup/organizations'
 import { dissectMember } from './workflows/dissectMember'
 import { findAndMergeMembersWithSamePlatformIdentitiesDifferentCapitalization } from './workflows/findAndMergeMembersWithSamePlatformIdentitiesDifferentCapitalization'
 import { findAndMergeMembersWithSameVerifiedEmailsInDifferentPlatforms } from './workflows/findAndMergeMembersWithSameVerifiedEmailsInDifferentPlatforms'
+import { fixActivityRelationsMemberId } from './workflows/fix-activityRelations-memberId'
 import { fixBotMembersAffiliation } from './workflows/fix-bot-members-affiliation'
 import { fixOrgIdentitiesWithWrongUrls } from './workflows/fixOrgIdentitiesWithWrongUrls'
 import { processLLMVerifiedMerges } from './workflows/processLLMVerifiedMerges'
@@ -24,4 +25,5 @@ export {
   cleanupDuplicateMembers,
   fixBotMembersAffiliation,
   blockOrganizationAffiliation,
+  fixActivityRelationsMemberId,
 }
diff --git a/services/apps/script_executor_worker/src/workflows/fix-activityRelations-memberId.ts b/services/apps/script_executor_worker/src/workflows/fix-activityRelations-memberId.ts
new file mode 100644
index 0000000000..95e851259a
--- /dev/null
+++ b/services/apps/script_executor_worker/src/workflows/fix-activityRelations-memberId.ts
@@ -0,0 +1,78 @@
+import { continueAsNew, proxyActivities } from '@temporalio/workflow'
+
+import { PlatformType } from '@crowd/types'
+
+import * as activities from '../activities'
+import { IFixActivityRelationsMemberIdArgs } from '../types'
+
+const {
+  findMembersWithWrongActivityRelations,
+  findMemberIdByUsernameAndPlatform,
+  moveActivityRelations,
+} = proxyActivities<typeof activities>({
+  startToCloseTimeout: '30 minutes',
+  retry: { maximumAttempts: 3, backoffCoefficient: 3 },
+})
+
+export async function fixActivityRelationsMemberId(
+  args: IFixActivityRelationsMemberIdArgs,
+): Promise<void> {
+  const BATCH_SIZE = args.batchSize ?? 500
+
+  const platforms = Object.values(PlatformType)
+  let currentPlatformIndex = args.currentPlatformIndex ?? 0
+
+  if (currentPlatformIndex >= platforms.length) {
+    console.log('All platforms exhausted. Workflow complete!')
+    return
+  }
+
+  const platform = platforms[currentPlatformIndex]
+
+  if (args.testRun) console.log('Processing platform:', platform)
+
+  // Take a batch from current platform
+  const records = await findMembersWithWrongActivityRelations(platform, BATCH_SIZE)
+
+  if (records.length === 0) {
+    console.log(`Platform ${platform} has no more records. Moving to next platform.`)
+    currentPlatformIndex++
+  } else {
+    // Process the batch immediately
+    await Promise.all(
+      records.map(async (record) => {
+        const correctMemberId = await findMemberIdByUsernameAndPlatform(
+          record.username,
+          record.platform,
+        )
+
+        if (args.testRun) {
+          console.log('Moving activity relations!', {
+            fromId: record.memberId,
+            toId: correctMemberId,
+            username: record.username,
+            platform: record.platform,
+          })
+        }
+
+        await moveActivityRelations(
+          record.memberId,
+          correctMemberId,
+          record.username,
+          record.platform,
+        )
+      }),
+    )
+  }
+
+  if (args.testRun) {
+    console.log('Test run completed - stopping after first batch!')
+    return
+  }
+
+  // Continue workflow for next batch (same platform or next platform)
+  await continueAsNew<typeof fixActivityRelationsMemberId>({
+    ...args,
+    currentPlatformIndex,
+  })
+}
diff --git a/services/libs/data-access-layer/src/old/apps/script_executor_worker/member.repo.ts b/services/libs/data-access-layer/src/old/apps/script_executor_worker/member.repo.ts
index adc4300b8d..f14d1a3332 100644
--- a/services/libs/data-access-layer/src/old/apps/script_executor_worker/member.repo.ts
+++ b/services/libs/data-access-layer/src/old/apps/script_executor_worker/member.repo.ts
@@ -3,6 +3,8 @@ import { Logger } from '@crowd/logging'
 import { IndexedEntityType } from '@crowd/opensearch/src/repo/indexing.data'
 import { IMember } from '@crowd/types'
 
+import { IDbActivityRelation } from '../../../activityRelations/types'
+
 import {
   IDuplicateMembersToCleanup,
   IFindMemberIdentitiesGroupedByPlatformResult,
@@ -382,6 +384,53 @@ class MemberRepository {
 
     return results.map((r) => r.memberId)
   }
+
+  public async findMembersWithIncorrectActivityRelations(
+    platform: string,
+    batchSize: number,
+  ): Promise<Partial<IDbActivityRelation>[]> {
+    return this.connection.query(
+      `
+      SELECT ar."memberId", ar."username", ar."platform"
+      FROM "activityRelations" ar
+      WHERE ar.platform = $(platform)
+        AND EXISTS (
+          SELECT 1
+          FROM "memberIdentities" mi
+          WHERE mi.platform = ar.platform
+            AND mi.value = ar.username
+            AND mi.type = 'username'
+            AND mi.verified = true
+            AND ar."memberId" != mi."memberId"
+      )
+      LIMIT $(batchSize);
+      `,
+      { platform, batchSize },
+    )
+  }
+
+  public async getMemberIdByUsernameAndPlatform(
+    username: string,
+    platform: string,
+  ): Promise<string> {
+    const result = await this.connection.oneOrNone(
+      `
+      SELECT "memberId" as "memberId"
+      FROM "memberIdentities"
+      WHERE value = $(username)
+        AND platform = $(platform)
+        AND verified = TRUE
+        AND type = 'username'
+      `,
+      { username, platform },
+    )
+
+    if (!result) {
+      throw new Error(`No verified member found!`)
+    }
+
+    return result.memberId
+  }
 }
 
 export default MemberRepository