diff --git a/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationPreview.test.tsx b/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationPreview.test.tsx
index 68cb32856d3..c6655a898da 100644
--- a/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationPreview.test.tsx
+++ b/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationPreview.test.tsx
@@ -1,12 +1,10 @@
-import { render, screen, waitFor, within } from '@testing-library/react';
-import userEvent from '@testing-library/user-event';
 import React from 'react';
+import { render, screen, waitFor, within, userEvent } from 'test/test-utils';
 import { byRole, byTestId, byText } from 'testing-library-selector';
 
 import { AccessControlAction } from 'app/types/accessControl';
 
 import 'core-js/stable/structured-clone';
-import { TestProvider } from '../../../../../../../test/helpers/TestProvider';
 import { MatcherOperator } from '../../../../../../plugins/datasource/alertmanager/types';
 import { Labels } from '../../../../../../types/unified-alerting-dto';
 import { mockApi, setupMswServer } from '../../../mockApi';
@@ -140,9 +138,7 @@ describe('NotificationPreview', () => {
     mockOneAlertManager();
     mockPreviewApiResponse(server, [{ labels: [{ tomato: 'red', avocate: 'green' }] }]);
 
-    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />, {
-      wrapper: TestProvider,
-    });
+    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />);
 
     await userEvent.click(ui.previewButton.get());
     await waitFor(() => {
@@ -166,9 +162,7 @@ describe('NotificationPreview', () => {
     mockTwoAlertManagers();
     mockPreviewApiResponse(server, [{ labels: [{ tomato: 'red', avocate: 'green' }] }]);
 
-    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />, {
-      wrapper: TestProvider,
-    });
+    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />);
     await waitFor(() => {
       expect(ui.loadingIndicator.query()).not.toBeInTheDocument();
     });
@@ -195,9 +189,7 @@ describe('NotificationPreview', () => {
     mockPreviewApiResponse(server, [{ labels: [{ tomato: 'red', avocate: 'green' }] }]);
     mockHasEditPermission(true);
 
-    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />, {
-      wrapper: TestProvider,
-    });
+    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />);
     await waitFor(() => {
       expect(ui.loadingIndicator.query()).not.toBeInTheDocument();
     });
@@ -219,9 +211,7 @@ describe('NotificationPreview', () => {
     mockPreviewApiResponse(server, [{ labels: [{ tomato: 'red', avocate: 'green' }] }]);
     mockHasEditPermission(false);
 
-    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />, {
-      wrapper: TestProvider,
-    });
+    render(<NotificationPreview alertQueries={[alertQuery]} customLabels={[]} condition="A" folder={folder} />);
     await waitFor(() => {
       expect(ui.loadingIndicator.query()).not.toBeInTheDocument();
     });
@@ -266,8 +256,7 @@ describe('NotificationPreviewByAlertmanager', () => {
         alertManagerSource={grafanaAlertManagerDataSource}
         potentialInstances={potentialInstances}
         onlyOneAM={true}
-      />,
-      { wrapper: TestProvider }
+      />
     );
 
     await waitFor(() => {
@@ -321,8 +310,7 @@ describe('NotificationPreviewByAlertmanager', () => {
         alertManagerSource={grafanaAlertManagerDataSource}
         potentialInstances={potentialInstances}
         onlyOneAM={true}
-      />,
-      { wrapper: TestProvider }
+      />
     );
 
     await waitFor(() => {
@@ -376,8 +364,7 @@ describe('NotificationPreviewByAlertmanager', () => {
         alertManagerSource={grafanaAlertManagerDataSource}
         potentialInstances={potentialInstances}
         onlyOneAM={true}
-      />,
-      { wrapper: TestProvider }
+      />
     );
 
     await waitFor(() => {
@@ -402,4 +389,80 @@ describe('NotificationPreviewByAlertmanager', () => {
     expect(matchingInstances1).toHaveTextContent(/job=prometheus/);
     expect(matchingInstances1).toHaveTextContent(/severity=warning/);
   });
+
+  describe('regex matching', () => {
+    it('does not match regex in middle of the word as alertmanager will anchor when queried via API', async () => {
+      const potentialInstances: Labels[] = [{ regexfield: 'foobarfoo' }];
+
+      mockApi(server).getAlertmanagerConfig(GRAFANA_RULES_SOURCE_NAME, (amConfigBuilder) =>
+        amConfigBuilder
+          .addReceivers((b) => b.withName('email'))
+          .withRoute((routeBuilder) =>
+            routeBuilder
+              .withReceiver('email')
+              .addRoute((rb) => rb.withReceiver('email').addMatcher('regexfield', MatcherOperator.regex, 'bar'))
+          )
+      );
+
+      render(
+        <NotificationPreviewByAlertManager
+          alertManagerSource={grafanaAlertManagerDataSource}
+          potentialInstances={potentialInstances}
+          onlyOneAM={true}
+        />
+      );
+
+      expect(await screen.findByText(/default policy/i)).toBeInTheDocument();
+      expect(screen.queryByText(/regexfield/)).not.toBeInTheDocument();
+    });
+
+    it('matches regex at the start of the word', async () => {
+      const potentialInstances: Labels[] = [{ regexfield: 'baaaaaaah' }];
+
+      mockApi(server).getAlertmanagerConfig(GRAFANA_RULES_SOURCE_NAME, (amConfigBuilder) =>
+        amConfigBuilder
+          .addReceivers((b) => b.withName('email'))
+          .withRoute((routeBuilder) =>
+            routeBuilder
+              .withReceiver('email')
+              .addRoute((rb) => rb.withReceiver('email').addMatcher('regexfield', MatcherOperator.regex, 'ba.*h'))
+          )
+      );
+
+      render(
+        <NotificationPreviewByAlertManager
+          alertManagerSource={grafanaAlertManagerDataSource}
+          potentialInstances={potentialInstances}
+          onlyOneAM={true}
+        />
+      );
+
+      expect(await screen.findByText(/regexfield/i)).toBeInTheDocument();
+    });
+
+    it('handles negated regex correctly', async () => {
+      const potentialInstances: Labels[] = [{ regexfield: 'thing' }];
+
+      mockApi(server).getAlertmanagerConfig(GRAFANA_RULES_SOURCE_NAME, (amConfigBuilder) =>
+        amConfigBuilder
+          .addReceivers((b) => b.withName('email'))
+          .withRoute((routeBuilder) =>
+            routeBuilder
+              .withReceiver('email')
+              .addRoute((rb) => rb.withReceiver('email').addMatcher('regexfield', MatcherOperator.notRegex, 'thing'))
+          )
+      );
+
+      render(
+        <NotificationPreviewByAlertManager
+          alertManagerSource={grafanaAlertManagerDataSource}
+          potentialInstances={potentialInstances}
+          onlyOneAM={true}
+        />
+      );
+
+      expect(await screen.findByText(/default policy/i)).toBeInTheDocument();
+      expect(screen.queryByText(/regexfield/i)).not.toBeInTheDocument();
+    });
+  });
 });
diff --git a/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationRoute.tsx b/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationRoute.tsx
index 1013135fe67..db0cfbddd19 100644
--- a/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationRoute.tsx
+++ b/public/app/features/alerting/unified/components/rule-editor/notificaton-preview/NotificationRoute.tsx
@@ -68,8 +68,7 @@ function NotificationRouteHeader({
         <Spacer />
         <Stack gap={2} direction="row" alignItems="center">
           <MetaText icon="layers-alt" data-testid="matching-instances">
-            {instancesCount ?? '-'}
-            <span>{pluralize('instance', instancesCount)}</span>
+            {instancesCount ?? '-'} {pluralize('instance', instancesCount)}
           </MetaText>
           <Stack gap={1} direction="row" alignItems="center">
             <div>
diff --git a/public/app/features/alerting/unified/utils/notification-policies.test.ts b/public/app/features/alerting/unified/utils/notification-policies.test.ts
index b6f12be2866..9dd13f9dfdd 100644
--- a/public/app/features/alerting/unified/utils/notification-policies.test.ts
+++ b/public/app/features/alerting/unified/utils/notification-policies.test.ts
@@ -476,6 +476,17 @@ describe('matchLabels', () => {
     expect(result).toHaveProperty('matches', false);
     expect(result.labelsMatch).toMatchSnapshot();
   });
+
+  it('does not match unanchored regular expressions', () => {
+    const result = matchLabels([['foo', MatcherOperator.regex, 'bar']], [['foo', 'barbarbar']]);
+    // This may seem unintuitive, but this is how Alertmanager matches, as it anchors the regex
+    expect(result.matches).toEqual(false);
+  });
+
+  it('matches regular expressions with wildcards', () => {
+    const result = matchLabels([['foo', MatcherOperator.regex, '.*bar.*']], [['foo', 'barbarbar']]);
+    expect(result.matches).toEqual(true);
+  });
 });
 
 describe('unquoteRouteMatchers', () => {
diff --git a/public/app/features/alerting/unified/utils/notification-policies.ts b/public/app/features/alerting/unified/utils/notification-policies.ts
index 8b419161078..8e60490d7f8 100644
--- a/public/app/features/alerting/unified/utils/notification-policies.ts
+++ b/public/app/features/alerting/unified/utils/notification-policies.ts
@@ -232,8 +232,17 @@ type OperatorPredicate = (labelValue: string, matcherValue: string) => boolean;
 const OperatorFunctions: Record<MatcherOperator, OperatorPredicate> = {
   [MatcherOperator.equal]: (lv, mv) => lv === mv,
   [MatcherOperator.notEqual]: (lv, mv) => lv !== mv,
-  [MatcherOperator.regex]: (lv, mv) => new RegExp(mv).test(lv),
-  [MatcherOperator.notRegex]: (lv, mv) => !new RegExp(mv).test(lv),
+  // At the time of writing, Alertmanager compiles to another (anchored) Regular Expression,
+  // so we should also anchor our UI matches for consistency with this behaviour
+  // https://github.com/prometheus/alertmanager/blob/fd37ce9c95898ca68be1ab4d4529517174b73c33/pkg/labels/matcher.go#L69
+  [MatcherOperator.regex]: (lv, mv) => {
+    const re = new RegExp(`^(?:${mv})$`);
+    return re.test(lv);
+  },
+  [MatcherOperator.notRegex]: (lv, mv) => {
+    const re = new RegExp(`^(?:${mv})$`);
+    return !re.test(lv);
+  },
 };
 
 function isLabelMatchInSet(matcher: ObjectMatcher, labels: Label[]): boolean {