diff --git a/app/models/bulk_import.rb b/app/models/bulk_import.rb
index 533d91089883ab6b49dfce075c22737f5e042ac2..f584f30ca96342ab5f0970cf58dd86850da40169 100644
--- a/app/models/bulk_import.rb
+++ b/app/models/bulk_import.rb
@@ -121,6 +121,23 @@ def parent_group_entity
     entities.group_entity.where(parent: nil).first
   end
 
+  def destination_group_roots
+    entities.where(parent: nil).filter_map do |entity|
+      entity.group || entity.project
+    end.map(&:root_ancestor).uniq
+  end
+
+  def namespaces_with_unassigned_placeholders
+    namespaces = destination_group_roots
+    namespace_ids = namespaces.collect(&:id)
+
+    reassignable_statuses = Import::SourceUser::STATUSES.slice(*Import::SourceUser::REASSIGNABLE_STATUSES).values
+    source_users = Import::SourceUser.for_namespace(namespace_ids).by_statuses(reassignable_statuses)
+    valid_namespace_ids = source_users.collect(&:namespace_id).uniq
+
+    namespaces.select { |namespace| valid_namespace_ids.include?(namespace.id) }
+  end
+
   def source_url
     configuration&.url
   end
diff --git a/app/presenters/import/pending_reassignment_alert_presenter.rb b/app/presenters/import/pending_reassignment_alert_presenter.rb
new file mode 100644
index 0000000000000000000000000000000000000000..1462867269c110770de6ff583160101db2c1f0b4
--- /dev/null
+++ b/app/presenters/import/pending_reassignment_alert_presenter.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Import
+  class PendingReassignmentAlertPresenter < Gitlab::View::Presenter::Simple
+    include Gitlab::Utils::StrongMemoize
+    include ActionView::Helpers::TagHelper
+    include SafeFormatHelper
+
+    presents ::BulkImport, as: :bulk_import
+
+    def show_alert?
+      Feature.enabled?(:importer_user_mapping, current_user) && groups_awaiting_placeholder_assignment.any?
+    end
+
+    def groups_awaiting_placeholder_assignment
+      return [] unless bulk_import
+
+      namespaces = bulk_import.namespaces_with_unassigned_placeholders
+      namespaces.select do |namespace|
+        namespace.owners.include?(current_user)
+      end
+    end
+    strong_memoize_attr :groups_awaiting_placeholder_assignment
+
+    def group_names
+      return '' if groups_awaiting_placeholder_assignment.empty?
+
+      groups_awaiting_placeholder_assignment.collect(&:name).to_sentence
+    end
+
+    def source_hostname
+      bulk_import.configuration.source_hostname
+    end
+
+    def title
+      s_('UserMapping|Placeholder users awaiting reassignment')
+    end
+
+    def body
+      safe_format(
+        s_('UserMapping|As part of the import, placeholder users were created on ' \
+          '%{group_names} and these users were assigned group membership and ' \
+          'contributions from %{source_hostname}. To reassign contributions from ' \
+          'placeholder users to GitLab users, visit the Members page of %{group_links}.'),
+        group_names: group_names,
+        source_hostname: source_hostname,
+        group_links: group_links
+      )
+    end
+
+    def group_links
+      placeholders = []
+      tag_pairs = []
+
+      groups_awaiting_placeholder_assignment.collect do |namespace|
+        placeholders << "%{group_#{namespace.id}_link_start}#{namespace.name}%{group_#{namespace.id}_link_end}"
+        tag_pairs << tag_pair(
+          tag.a(href: group_group_members_path(namespace)),
+          :"group_#{namespace.id}_link_start",
+          :"group_#{namespace.id}_link_end"
+        )
+      end
+
+      safe_format(placeholders.to_sentence, *tag_pairs)
+    end
+  end
+end
diff --git a/app/views/import/bulk_imports/history.html.haml b/app/views/import/bulk_imports/history.html.haml
index 81eb08cfbc59278bd6d015bcc07f074061bb5649..13a88867d5a1763f5fedbc2223750d5590e3aa1c 100644
--- a/app/views/import/bulk_imports/history.html.haml
+++ b/app/views/import/bulk_imports/history.html.haml
@@ -7,4 +7,13 @@
 
 - add_page_specific_style 'page_bundles/import'
 
+- pending_reassignment_presenter = Gitlab::View::Presenter::Factory.new(@bulk_import, current_user: current_user, presenter_class: ::Import::PendingReassignmentAlertPresenter).fabricate!
+- if pending_reassignment_presenter.show_alert?
+  = render Pajamas::AlertComponent.new(variant: :notice, title: pending_reassignment_presenter.title, alert_options: { class: 'gl-mt-4' }) do |c|
+    - c.with_body do
+      = pending_reassignment_presenter.body
+    - c.with_actions do
+      = render Pajamas::ButtonComponent.new(variant: :default, href: help_page_path('user/project/import/index', anchor: 'placeholder-users'), button_options: { class: 'deferred-link gl-alert-action', rel: 'noreferrer noopener' }, target: '_blank') do
+        = _('Learn more')
+
 #import-history-mount-element{ data: { id: @bulk_import&.id, details_path: failures_import_bulk_import_path(':id', ':entity_id'), realtime_changes_path: realtime_changes_import_bulk_imports_path(format: :json) } }
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index 1e2ea1f4b40f1dd09bc4747bd6dd060ec9f15607..024571676b34dee76d5523d6eb2d775dd8a4b539 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -58450,6 +58450,9 @@ msgstr ""
 msgid "UserMapping|Approve reassignment"
 msgstr ""
 
+msgid "UserMapping|As part of the import, placeholder users were created on %{group_names} and these users were assigned group membership and contributions from %{source_hostname}. To reassign contributions from placeholder users to GitLab users, visit the Members page of %{group_links}."
+msgstr ""
+
 msgid "UserMapping|Awaiting reassignment"
 msgstr ""
 
@@ -58501,6 +58504,9 @@ msgstr ""
 msgid "UserMapping|Placeholder user was made permanent."
 msgstr ""
 
+msgid "UserMapping|Placeholder users awaiting reassignment"
+msgstr ""
+
 msgid "UserMapping|Placeholders"
 msgstr ""
 
diff --git a/spec/helpers/import_helper_spec.rb b/spec/helpers/import_helper_spec.rb
index 7a5a69ea5b55a0c4b9c039084d59b9d938920446..2909d451af9bb760e302a0ecb30cdb5135d4e37c 100644
--- a/spec/helpers/import_helper_spec.rb
+++ b/spec/helpers/import_helper_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe ImportHelper do
+RSpec.describe ImportHelper, feature_category: :importers do
   describe '#sanitize_project_name' do
     it 'removes leading tildes' do
       expect(helper.sanitize_project_name('~~root')).to eq('root')
diff --git a/spec/models/bulk_import_spec.rb b/spec/models/bulk_import_spec.rb
index 5870edfb25ca8c5bec8f6b45c2506e486b31c4b5..1d8759ea8282b8cca38f4606f98ce53a58dd78c4 100644
--- a/spec/models/bulk_import_spec.rb
+++ b/spec/models/bulk_import_spec.rb
@@ -210,11 +210,32 @@ def supports_block_expectations?
 
     let_it_be(:root_node) { create(:bulk_import_entity) }
 
-    it 'returns the topmost group note of the import entity tree' do
+    it 'returns the topmost node of the first tree of the import entity structure' do
       expect(import.parent_group_entity).to eq(root_node)
     end
   end
 
+  describe '#destination_group_roots' do
+    subject(:import) do
+      create(:bulk_import, :started, entities: [
+        root_project_entity,
+        root_group_entity,
+        create(:bulk_import_entity, parent: root_group_entity)
+      ])
+    end
+
+    let_it_be(:project_namespace) { create(:group) }
+    let_it_be(:project) { create(:project, namespace: project_namespace) }
+    let_it_be(:root_project_entity) { create(:bulk_import_entity, :project_entity, project: project) }
+
+    let_it_be(:top_level_group) { create(:group) }
+    let_it_be(:root_group_entity) { create(:bulk_import_entity, :group_entity, group: top_level_group) }
+
+    it 'returns the topmost group nodes of the import entity tree' do
+      expect(import.destination_group_roots).to match_array([project_namespace, top_level_group])
+    end
+  end
+
   describe '#source_url' do
     it 'returns migration source url via configuration' do
       import = create(:bulk_import, :with_configuration)
@@ -230,4 +251,27 @@ def supports_block_expectations?
       end
     end
   end
+
+  describe '#namespaces_with_unassigned_placeholders' do
+    let_it_be(:group) { create(:group) }
+    let_it_be(:entity) do
+      create(:bulk_import_entity, :group_entity, bulk_import: finished_bulk_import, group: group)
+    end
+
+    before do
+      create_list(:import_source_user, 5, :completed, namespace: group)
+    end
+
+    context 'when all placeholders have been assigned' do
+      it { expect(finished_bulk_import.namespaces_with_unassigned_placeholders).to be_empty }
+    end
+
+    context 'when some placeholders have not been assigned' do
+      before do
+        create(:import_source_user, :pending_reassignment, namespace: group)
+      end
+
+      it { expect(finished_bulk_import.namespaces_with_unassigned_placeholders).to include(group) }
+    end
+  end
 end
diff --git a/spec/presenters/import/pending_reassignment_alert_presenter_spec.rb b/spec/presenters/import/pending_reassignment_alert_presenter_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..a48e67f8da57a123717195a67ef7b995a7a6961d
--- /dev/null
+++ b/spec/presenters/import/pending_reassignment_alert_presenter_spec.rb
@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Import::PendingReassignmentAlertPresenter, :aggregate_failures, feature_category: :importers do
+  include SafeFormatHelper
+
+  let_it_be(:user) { build_stubbed(:user) }
+  let_it_be(:bulk_import) { build_stubbed(:bulk_import, :with_configuration) }
+  let(:presenter) { described_class.new(bulk_import, current_user: user) }
+  let_it_be(:namespaces) { [] }
+
+  before do
+    namespaces.each do |namespace|
+      allow(namespace).to receive(:owners).and_return([user])
+    end
+
+    allow(bulk_import).to receive(:namespaces_with_unassigned_placeholders).and_return(namespaces)
+  end
+
+  describe '#title' do
+    subject { presenter.title }
+
+    it { is_expected.to eq(s_('UserMapping|Placeholder users awaiting reassignment')) }
+  end
+
+  describe '#body' do
+    subject { presenter.body }
+
+    it do
+      is_expected.to eq(
+        safe_format(
+          s_('UserMapping|As part of the import, placeholder users were created on ' \
+            '%{group_names} and these users were assigned group membership and ' \
+            'contributions from %{source_hostname}. To reassign contributions from ' \
+            'placeholder users to GitLab users, visit the Members page of %{group_links}.'),
+          group_names: '',
+          source_hostname: 'gitlab.example',
+          group_links: ''
+        ))
+    end
+  end
+
+  context 'with no top level groups' do
+    let_it_be(:namespaces) { [] }
+
+    it 'presents the import values' do
+      expect(presenter.show_alert?).to eq(false)
+    end
+  end
+
+  context 'with one top level group' do
+    let_it_be(:namespaces) do
+      source_users = build_stubbed(:import_source_user)
+      [build_stubbed(:group, id: 1, name: 'blink', import_source_users: [source_users])]
+    end
+
+    it 'presents the import values' do
+      expect(presenter.show_alert?).to eq(true)
+      expect(presenter.group_links).to eq("<a href=\"/groups/blink/-/group_members\">blink</a>")
+      expect(presenter.groups_awaiting_placeholder_assignment).to match_array(namespaces)
+      expect(presenter.group_names).to eq('blink')
+      expect(presenter.source_hostname).to eq('gitlab.example')
+    end
+
+    context 'when importer_user_mapping feature flag is disabled' do
+      before do
+        stub_feature_flags(importer_user_mapping: false)
+      end
+
+      it 'presents the import values' do
+        expect(presenter.show_alert?).to eq(false)
+      end
+    end
+  end
+
+  context 'with multiple top level groups' do
+    let_it_be(:namespaces) do
+      [
+        build_stubbed(:group, id: 1, name: 'blink'),
+        build_stubbed(:group, id: 3, name: 'marquee'),
+        build_stubbed(:group, id: 7, name: 'details')
+      ]
+    end
+
+    it 'presents the import values' do
+      expect(presenter.show_alert?).to eq(true)
+      expect(presenter.group_links).to eq(
+        "<a href=\"/groups/blink/-/group_members\">blink</a>, " \
+          "<a href=\"/groups/marquee/-/group_members\">marquee</a>, " \
+          "and <a href=\"/groups/details/-/group_members\">details</a>"
+      )
+      expect(presenter.groups_awaiting_placeholder_assignment).to match_array(namespaces)
+      expect(presenter.group_names).to eq('blink, marquee, and details')
+      expect(presenter.source_hostname).to eq('gitlab.example')
+    end
+
+    context 'when the current user is not an owner of a top level group' do
+      it 'excludes that group from the results' do
+        allow(namespaces[0]).to receive(:owners).and_return([])
+
+        expect(presenter.groups_awaiting_placeholder_assignment).to match_array(namespaces[1..])
+      end
+    end
+  end
+end