diff --git a/app/services/encryption/multi_region_kms_profile_migrator.rb b/app/services/encryption/multi_region_kms_profile_migrator.rb
new file mode 100644
index 00000000000..31032b2636d
--- /dev/null
+++ b/app/services/encryption/multi_region_kms_profile_migrator.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+module Encryption
+  class MultiRegionKmsProfileMigrator
+    include ::NewRelic::Agent::MethodTracer
+
+    attr_reader :profile
+
+    def initialize(profile)
+      @profile = profile
+    end
+
+    def migrate!
+      profile.with_lock do
+        if profile.encrypted_pii.blank? && profile.encrypted_pii_recovery.blank?
+          raise "Profile##{profile.id} is missing encrypted_pii or encrypted_pii_recovery"
+        end
+
+        next if profile.encrypted_pii_multi_region.present? &&
+                profile.encrypted_pii_recovery_multi_region.present?
+
+        if profile.encrypted_pii.present? && profile.encrypted_pii_multi_region.blank?
+          encrypted_pii_multi_region = migrate_ciphertext(profile.encrypted_pii)
+          profile.update!(
+            encrypted_pii_multi_region: encrypted_pii_multi_region,
+          )
+        end
+        if profile.encrypted_pii_recovery.present? &&
+           profile.encrypted_pii_recovery_multi_region.blank?
+          encrypted_pii_recovery_multi_region = migrate_ciphertext(profile.encrypted_pii_recovery)
+          profile.update!(
+            encrypted_pii_recovery_multi_region: encrypted_pii_recovery_multi_region,
+          )
+        end
+
+        profile
+      end
+    end
+
+    private
+
+    def migrate_ciphertext(ciphertext_string)
+      ciphertext = Encryption::Encryptors::PiiEncryptor::Ciphertext.parse_from_string(
+        ciphertext_string,
+      )
+
+      aes_encrypted_data = multi_region_kms_client.decrypt(
+        ciphertext.encrypted_data, kms_encryption_context
+      )
+      multi_region_kms_encrypted_data = multi_region_kms_client.encrypt(
+        aes_encrypted_data, kms_encryption_context
+      )
+      Encryption::Encryptors::PiiEncryptor::Ciphertext.new(
+        multi_region_kms_encrypted_data,
+        ciphertext.salt,
+        ciphertext.cost,
+      )
+    end
+
+    def kms_encryption_context
+      {
+        'context' => 'pii-encryption',
+        'user_uuid' => profile.user.uuid,
+      }
+    end
+
+    def multi_region_kms_client
+      @multi_region_kms_client ||= KmsClient.new(
+        kms_key_id: IdentityConfig.store.aws_kms_multi_region_key_id,
+      )
+    end
+  end
+end
diff --git a/lib/tasks/backfill_profiles.rake b/lib/tasks/backfill_profiles.rake
new file mode 100644
index 00000000000..0cdf843891d
--- /dev/null
+++ b/lib/tasks/backfill_profiles.rake
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+namespace :profiles do
+  desc 'Backfill the encrypted_pii_multi_region value column.'
+
+  ##
+  # Usage:
+  #
+  # Print pending updates
+  # bundle exec rake profiles:backfill_encrypted_pii_multi_region
+  #
+  # Commit updates
+  # bundle exec rake profiles:backfill_encrypted_pii_multi_region UPDATE_PROFILES=true
+  #
+  task backfill_encrypted_pii_multi_region: :environment do |_task, _args|
+    profile_limit = ENV['PROFILE_LIMIT'].to_i
+    statement_timeout_seconds = ENV['STATEMENT_TIMEOUT_SECONDS'].to_i
+    update_profiles = ENV['UPDATE_PROFILES'] == 'true'
+
+    profiles = Profile.transaction do
+      quoted_timeout = Profile.connection.quote(statement_timeout_seconds * 1000)
+      Profile.connection.execute("SET LOCAL statement_timeout = #{quoted_timeout}")
+
+      Profile.where(
+        <<-SQL,
+        (encrypted_pii IS NOT NULL AND encrypted_pii_multi_region IS NULL) OR
+        (encrypted_pii_recovery IS NOT NULL AND encrypted_pii_recovery_multi_region IS NULL)
+        SQL
+      ).limit(profile_limit)
+    end
+
+    Rails.logger.info("#{profiles.count} profiles found")
+    profiles.each do |profile|
+      Rails.logger.info(profile.id)
+      Encryption::MultiRegionKmsProfileMigrator.new(profile).migrate! if update_profiles
+    end
+  end
+end
diff --git a/spec/lib/tasks/backfill_profiles_rake_spec.rb b/spec/lib/tasks/backfill_profiles_rake_spec.rb
new file mode 100644
index 00000000000..789d44bc40f
--- /dev/null
+++ b/spec/lib/tasks/backfill_profiles_rake_spec.rb
@@ -0,0 +1,82 @@
+require 'rails_helper'
+require 'rake'
+
+RSpec.describe 'backfill profiles tasks' do
+  let(:profile_limit) { '10' }
+  let(:update_profiles) { nil }
+  let(:env) do
+    {
+      'PROFILE_LIMIT' => profile_limit,
+      'STATEMENT_TIMEOUT_SECONDS' => '100',
+      'UPDATE_PROFILES' => update_profiles,
+    }
+  end
+
+  before do
+    Rake.application.rake_require 'tasks/backfill_profiles'
+    Rake::Task.define_task(:environment)
+    Rake::Task['profiles:backfill_encrypted_pii_multi_region'].reenable
+    stub_const('ENV', env)
+  end
+
+  describe 'dev:backfill_encrypted_pii_multi_region' do
+    it 'logs data about profiles being migrated' do
+      profile = create_profile_that_needs_to_be_migrated
+      create(:profile, :with_pii)
+
+      expect(Rails.logger).to receive(:info).with('1 profiles found')
+      expect(Rails.logger).to receive(:info).with(profile.id)
+
+      Rake::Task['profiles:backfill_encrypted_pii_multi_region'].invoke
+    end
+
+    context 'with update_profiles disabled' do
+      it 'does not update profiles' do
+        profile = create_profile_that_needs_to_be_migrated
+
+        expect(profile.encrypted_pii).to be_present
+        expect(profile.encrypted_pii_recovery).to be_present
+        expect(profile.encrypted_pii_multi_region).to_not be_present
+        expect(profile.encrypted_pii_recovery_multi_region).to_not be_present
+
+        Rake::Task['profiles:backfill_encrypted_pii_multi_region'].invoke
+
+        expect(profile.encrypted_pii).to be_present
+        expect(profile.encrypted_pii_recovery).to be_present
+        expect(profile.encrypted_pii_multi_region).to_not be_present
+        expect(profile.encrypted_pii_recovery_multi_region).to_not be_present
+      end
+    end
+
+    context 'with update_profiles enabled' do
+      let(:update_profiles) { 'true' }
+
+      it 'does update profiles' do
+        profile = create_profile_that_needs_to_be_migrated
+        expect(profile.encrypted_pii).to be_present
+        expect(profile.encrypted_pii_recovery).to be_present
+        expect(profile.encrypted_pii_multi_region).to_not be_present
+        expect(profile.encrypted_pii_recovery_multi_region).to_not be_present
+
+        Rake::Task['profiles:backfill_encrypted_pii_multi_region'].invoke
+
+        profile.reload
+        expect(profile.encrypted_pii).to be_present
+        expect(profile.encrypted_pii_recovery).to be_present
+        expect(profile.encrypted_pii_multi_region).to be_present
+        expect(profile.encrypted_pii_recovery_multi_region).to be_present
+      end
+    end
+  end
+
+  def create_profile_that_needs_to_be_migrated
+    profile = create(:profile, :with_pii)
+    profile.update(
+      encrypted_pii: profile.encrypted_pii_multi_region,
+      encrypted_pii_multi_region: nil,
+      encrypted_pii_recovery: profile.encrypted_pii_recovery_multi_region,
+      encrypted_pii_recovery_multi_region: nil,
+    )
+    profile
+  end
+end
diff --git a/spec/services/encryption/kms_client_spec.rb b/spec/services/encryption/kms_client_spec.rb
index 4b4a46e94a5..dab6a9771ca 100644
--- a/spec/services/encryption/kms_client_spec.rb
+++ b/spec/services/encryption/kms_client_spec.rb
@@ -12,29 +12,17 @@
     )
 
     # rubocop:disable Layout/LineLength
-    stub_mapped_aws_kms_client(
-      [
-        { plaintext: 'a' * 3000, ciphertext: 'us-north-1:kms1', key_id: key_id, region: 'us-north-1' },
-        { plaintext: 'b' * 3000, ciphertext: 'us-north-1:kms2', key_id: key_id, region: 'us-north-1' },
-        { plaintext: 'c' * 3000, ciphertext: 'us-north-1:kms3', key_id: key_id, region: 'us-north-1' },
-      ],
-    )
+    if kms_enabled
+      stub_mapped_aws_kms_client(
+        [
+          { plaintext: 'a' * 3000, ciphertext: 'us-north-1:kms1', key_id: key_id, region: 'us-north-1' },
+          { plaintext: 'b' * 3000, ciphertext: 'us-north-1:kms2', key_id: key_id, region: 'us-north-1' },
+          { plaintext: 'c' * 3000, ciphertext: 'us-north-1:kms3', key_id: key_id, region: 'us-north-1' },
+        ],
+      )
+    end
     # rubocop:enable Layout/LineLength
 
-    encryptor = Encryption::Encryptors::AesEncryptor.new
-    {
-      'a' * 3000 => 'local1',
-      'b' * 3000 => 'local2',
-      'c' * 3000 => 'local3',
-    }.each do |plaintext, ciphertext|
-      allow(encryptor).to receive(:encrypt)
-        .with(plaintext, local_encryption_key)
-        .and_return(ciphertext)
-      allow(encryptor).to receive(:decrypt)
-        .with(ciphertext, local_encryption_key)
-        .and_return(plaintext)
-    end
-    allow(Encryption::Encryptors::AesEncryptor).to receive(:new).and_return(encryptor)
     allow(FeatureManagement).to receive(:use_kms?).and_return(kms_enabled)
     allow(IdentityConfig.store).to receive(:aws_region).and_return(aws_region)
     allow(IdentityConfig.store).to receive(:aws_kms_key_id).and_return(key_id)
@@ -46,14 +34,6 @@
   let(:encryption_context) { { 'context' => 'attribute-bundle', 'user_id' => '123-abc-456-def' } }
   let(:log_timestamp) { Time.utc(2025, 2, 28, 15, 30, 1) }
 
-  let(:local_encryption_key) do
-    OpenSSL::HMAC.digest(
-      'sha256',
-      IdentityConfig.store.password_pepper,
-      '123-abc-456-defattribute-bundlecontextuser_id',
-    )
-  end
-
   let(:aws_region) { 'us-north-1' }
 
   let(:kms_ciphertext) do
@@ -64,10 +44,6 @@
     ].map { |c| Base64.strict_encode64(c) }.to_json
   end
 
-  let(:local_ciphertext) do
-    'LOCc' + %w[local1 local2 local3].map { |c| Base64.strict_encode64(c) }.to_json
-  end
-
   let(:kms_enabled) { true }
 
   describe '#encrypt' do
@@ -111,7 +87,7 @@
       it 'encrypts with a local key' do
         result = subject.encrypt(plaintext, encryption_context)
 
-        expect(result).to eq(local_ciphertext)
+        expect(result).to_not include(plaintext)
       end
     end
 
@@ -136,8 +112,11 @@
     end
 
     context 'with a ciphertext encrypted with a local key' do
+      let(:kms_enabled) { false }
+
       it 'decrypts the ciphertext with a local key' do
-        result = subject.decrypt(local_ciphertext, encryption_context)
+        ciphertext = subject.encrypt(plaintext, encryption_context)
+        result = subject.decrypt(ciphertext, encryption_context)
 
         expect(result).to eq(plaintext)
       end
diff --git a/spec/services/encryption/multi_region_kms_profile_migrator_spec.rb b/spec/services/encryption/multi_region_kms_profile_migrator_spec.rb
new file mode 100644
index 00000000000..62c503890cb
--- /dev/null
+++ b/spec/services/encryption/multi_region_kms_profile_migrator_spec.rb
@@ -0,0 +1,115 @@
+require 'rails_helper'
+
+RSpec.describe Encryption::MultiRegionKmsProfileMigrator do
+  let(:profile) { create(:profile, pii: pii) }
+  let(:user_password) { profile.user.password }
+  let(:personal_key) { PersonalKeyGenerator.new(profile.user).normalize(profile.personal_key) }
+  let(:pii) do
+    {
+      dob: '1920-01-01',
+      ssn: '666-66-1234',
+      first_name: 'Jane',
+      last_name: 'Doe',
+      zipcode: '20001',
+    }
+  end
+
+  subject { described_class.new(profile) }
+
+  before do
+    allow(IdentityConfig.store).to receive(:aws_kms_multi_region_read_enabled).and_return(true)
+  end
+
+  describe '#migrate!' do
+    context 'for a user without multi-region ciphertexts' do
+      it 'migrates the single-region ciphertext and saves it to the profile' do
+        pii_encryptor = Encryption::Encryptors::PiiEncryptor.new(user_password)
+        profile.encrypted_pii = pii_encryptor.encrypt(pii.to_json, user_uuid: profile.user.uuid)
+        recovery_pii_encryptor = Encryption::Encryptors::PiiEncryptor.new(personal_key)
+        profile.encrypted_pii_recovery = recovery_pii_encryptor.encrypt(
+          pii.to_json, user_uuid: profile.user.uuid
+        )
+        profile.encrypted_pii_multi_region = nil
+        profile.encrypted_pii_recovery_multi_region = nil
+        profile.save
+        subject.migrate!
+
+        pii_encryptor = Encryption::Encryptors::PiiEncryptor.new(user_password)
+
+        single_region_pii = pii_encryptor.decrypt(
+          profile.encrypted_pii,
+          user_uuid: profile.user.uuid,
+        )
+        multi_region_pii = pii_encryptor.decrypt(
+          profile.encrypted_pii_multi_region,
+          user_uuid: profile.user.uuid,
+        )
+
+        expect(profile.encrypted_pii).to_not be_blank
+        expect(profile.encrypted_pii_multi_region).to_not be_blank
+        expect(profile.encrypted_pii).to_not eq(profile.encrypted_pii_multi_region)
+        expect(single_region_pii).to eq(multi_region_pii)
+
+        pii_recovery_encryptor = Encryption::Encryptors::PiiEncryptor.new(personal_key)
+
+        single_region_pii_recovery = pii_recovery_encryptor.decrypt(
+          profile.encrypted_pii_recovery,
+          user_uuid: profile.user.uuid,
+        )
+        multi_region_pii_recovery = pii_recovery_encryptor.decrypt(
+          profile.encrypted_pii_recovery_multi_region,
+          user_uuid: profile.user.uuid,
+        )
+
+        expect(profile.encrypted_pii_recovery).to_not be_blank
+        expect(profile.encrypted_pii_recovery_multi_region).to_not be_blank
+        expect(profile.encrypted_pii_recovery).to_not eq(
+          profile.encrypted_pii_recovery_multi_region,
+        )
+
+        expect(single_region_pii_recovery).to eq(multi_region_pii_recovery)
+      end
+    end
+
+    context 'for a user with multi-region ciphertexts' do
+      it 'does not modify the profile record' do
+        expect do
+          pii_encryptor = Encryption::Encryptors::PiiEncryptor.new(user_password)
+          profile.encrypted_pii = pii_encryptor.encrypt(pii.to_json, user_uuid: profile.user.uuid)
+          recovery_pii_encryptor = Encryption::Encryptors::PiiEncryptor.new(personal_key)
+          profile.encrypted_pii_recovery = recovery_pii_encryptor.encrypt(
+            pii.to_json, user_uuid: profile.user.uuid
+          )
+          profile.save
+
+          subject.migrate!
+        end.to_not change {
+          profile.attributes.slice(
+            :encrypted_pii,
+            :encrypted_pii_multi_region,
+            :encrypted_pii_recovery,
+            :encrypted_pii_recovery_multi_region,
+          )
+        }
+      end
+    end
+
+    context 'for a user without multi-region or single-region ciphertexts' do
+      before do
+        profile.update!(
+          encrypted_pii: nil,
+          encrypted_pii_multi_region: nil,
+          encrypted_pii_recovery: nil,
+          encrypted_pii_recovery_multi_region: nil,
+        )
+      end
+
+      it 'does not modify the profile record' do
+        expect { subject.migrate! }.to raise_error(
+          RuntimeError,
+          "Profile##{profile.id} is missing encrypted_pii or encrypted_pii_recovery",
+        )
+      end
+    end
+  end
+end