diff --git a/.changeset/new-rocks-explode.md b/.changeset/new-rocks-explode.md
new file mode 100644
index 000000000..4038d69b1
--- /dev/null
+++ b/.changeset/new-rocks-explode.md
@@ -0,0 +1,5 @@
+---
+"gitbook": minor
+---
+
+Support site announcement banner
diff --git a/packages/gitbook/src/components/Announcement/Announcement.tsx b/packages/gitbook/src/components/Announcement/Announcement.tsx
new file mode 100644
index 000000000..0497ce3ab
--- /dev/null
+++ b/packages/gitbook/src/components/Announcement/Announcement.tsx
@@ -0,0 +1,32 @@
+import { resolveContentRef } from '@/lib/references';
+import type { GitBookSiteContext } from '@v2/lib/context';
+import { AnnouncementBanner } from './AnnouncementBanner';
+
+/**
+ * Server-side component to resolve content refs and pass down to client-side component
+ */
+export async function Announcement(props: {
+    context: GitBookSiteContext;
+}) {
+    const { context } = props;
+    const { customization } = context;
+
+    if (
+        !customization.announcement ||
+        !customization.announcement.enabled ||
+        !customization.announcement.message
+    ) {
+        return null;
+    }
+
+    const resolvedContentRef = customization.announcement?.link
+        ? await resolveContentRef(customization.announcement?.link?.to, context)
+        : null;
+
+    return (
+        <AnnouncementBanner
+            announcement={customization.announcement}
+            contentRef={resolvedContentRef}
+        />
+    );
+}
diff --git a/packages/gitbook/src/components/Announcement/AnnouncementBanner.tsx b/packages/gitbook/src/components/Announcement/AnnouncementBanner.tsx
new file mode 100644
index 000000000..cbfd49131
--- /dev/null
+++ b/packages/gitbook/src/components/Announcement/AnnouncementBanner.tsx
@@ -0,0 +1,126 @@
+'use client';
+
+import * as storage from '@/lib/local-storage';
+import type { ResolvedContentRef } from '@/lib/references';
+import { tcls } from '@/lib/tailwind';
+import type { CustomizationAnnouncement } from '@gitbook/api';
+import { Icon, type IconName } from '@gitbook/icons';
+import Link from 'next/link';
+import { CONTAINER_STYLE } from '../layout';
+import { linkStyles } from '../primitives';
+import { ANNOUNCEMENT_CSS_CLASS, ANNOUNCEMENT_STORAGE_KEY } from './constants';
+
+/**
+ * Client-side component to enable closing the banner
+ */
+export function AnnouncementBanner(props: {
+    announcement: CustomizationAnnouncement;
+    contentRef: ResolvedContentRef | null;
+}) {
+    const { announcement, contentRef } = props;
+
+    const hasLink = announcement.link && contentRef?.href;
+    const closeable = announcement.style !== 'danger';
+
+    const Tag = hasLink ? Link : 'div';
+    const style = BANNER_STYLES[announcement.style];
+
+    return (
+        <div className="announcement-banner scroll-nojump theme-bold:bg-header-background pt-4 pb-2">
+            <div className={tcls('relative', CONTAINER_STYLE)}>
+                <Tag
+                    href={contentRef?.href ?? ''}
+                    className={tcls(
+                        'flex w-full items-start justify-center overflow-hidden rounded-md straight-corners:rounded-none px-4 py-3 text-neutral-strong text-sm theme-bold:ring-1 theme-gradient:ring-1 ring-inset transition-colors',
+                        style.container,
+                        closeable && 'pr-12',
+                        hasLink && style.hover
+                    )}
+                >
+                    <Icon
+                        icon={style.icon as IconName}
+                        className={`mt-0.5 mr-3 size-4 shrink-0 ${style.iconColor}`}
+                    />
+                    <div>
+                        {announcement.message}
+                        {hasLink ? (
+                            <div className={tcls(linkStyles, style.link, 'ml-1 inline')}>
+                                {contentRef?.icon ? (
+                                    <span className="mr-1 ml-2 *:inline">{contentRef?.icon}</span>
+                                ) : null}
+                                {announcement.link?.title && (
+                                    <span className="mr-1">{announcement.link?.title}</span>
+                                )}
+                                <Icon
+                                    icon={
+                                        announcement.link?.to.kind === 'url'
+                                            ? 'arrow-up-right'
+                                            : 'chevron-right'
+                                    }
+                                    className={tcls('mb-0.5 inline size-3')}
+                                />
+                            </div>
+                        ) : null}
+                    </div>
+                </Tag>
+                {closeable ? (
+                    <button
+                        className={`absolute top-0 right-4 mt-2 mr-2 rounded straight-corners:rounded-none p-1.5 transition-all hover:ring-1 sm:right-6 md:right-8 ${style.close}`}
+                        type="button"
+                        onClick={dismissAnnouncement}
+                    >
+                        <Icon icon="close" className="size-4" />
+                    </button>
+                ) : null}
+            </div>
+        </div>
+    );
+}
+
+/**
+ * Dismiss the announcement banner and store the dismissal state in local storage.
+ * @see AnnouncementScript
+ */
+function dismissAnnouncement() {
+    storage.setItem(ANNOUNCEMENT_STORAGE_KEY, {
+        visible: false,
+        at: Date.now(),
+    });
+
+    document.documentElement.classList.add(ANNOUNCEMENT_CSS_CLASS);
+}
+
+const BANNER_STYLES = {
+    info: {
+        container: 'bg-info ring-info-subtle',
+        hover: 'hover:bg-info-hover active:bg-info-active',
+        icon: 'circle-info',
+        iconColor: 'text-info-subtle',
+        close: 'hover:bg-tint-base hover:ring-info-subtle',
+        link: '',
+    },
+    warning: {
+        container: 'bg-warning decoration-warning/6 ring-warning-subtle',
+        hover: 'hover:bg-warning-hover',
+        icon: 'circle-exclamation',
+        iconColor: 'text-warning-subtle',
+        close: 'hover:bg-tint-base hover:ring-warning-subtle',
+        link: 'links-default:text-warning links-default:hover:text-warning-strong links-default:decoration-warning/6 links-accent:decoration-warning',
+    },
+    danger: {
+        container: 'bg-danger decoration-danger/6 ring-danger-subtle',
+        hover: 'hover:bg-danger-hover',
+        icon: 'triangle-exclamation',
+        iconColor: 'text-danger-subtle',
+        close: 'hover:bg-tint-base hover:ring-danger-subtle',
+        link: 'links-default:text-danger links-default:hover:text-danger-strong links-default:decoration-danger/6 links-accent:decoration-danger',
+    },
+    success: {
+        container: 'bg-success decoration-success/6 ring-success-subtle',
+        hover: 'hover:bg-success-hover',
+        icon: 'circle-check',
+        iconColor: 'text-success-subtle',
+        close: 'hover:bg-tint-base hover:ring-success-subtle',
+        link: 'links-default:text-success links-default:hover:text-success-strong links-default:decoration-success/6 links-accent:decoration-success',
+    },
+};
diff --git a/packages/gitbook/src/components/Announcement/AnnouncementDismissedScript.tsx b/packages/gitbook/src/components/Announcement/AnnouncementDismissedScript.tsx
new file mode 100644
index 000000000..2956e55ba
--- /dev/null
+++ b/packages/gitbook/src/components/Announcement/AnnouncementDismissedScript.tsx
@@ -0,0 +1,29 @@
+'use client';
+
+import {
+    ANNOUNCEMENT_CSS_CLASS,
+    ANNOUNCEMENT_DAYS_TILL_RESET,
+    ANNOUNCEMENT_STORAGE_KEY,
+} from './constants';
+import { checkStorageForDismissedScript } from './script';
+
+/**
+ * Inject a script to read the local storage state for the announcement banner and apply the appropriate CSS class to the <html> element as early as possible.
+ * Bypasses react state to prevent flickering.
+ */
+export function AnnouncementDismissedScript() {
+    const scriptArgs = JSON.stringify([
+        ANNOUNCEMENT_STORAGE_KEY,
+        ANNOUNCEMENT_DAYS_TILL_RESET,
+        ANNOUNCEMENT_CSS_CLASS,
+    ]).slice(1, -1);
+
+    return (
+        <script
+            suppressHydrationWarning
+            dangerouslySetInnerHTML={{
+                __html: `(${checkStorageForDismissedScript.toString()})(${scriptArgs})`,
+            }}
+        />
+    );
+}
diff --git a/packages/gitbook/src/components/Announcement/constants.ts b/packages/gitbook/src/components/Announcement/constants.ts
new file mode 100644
index 000000000..ceca2c207
--- /dev/null
+++ b/packages/gitbook/src/components/Announcement/constants.ts
@@ -0,0 +1,12 @@
+/**
+ * The local storage key for the announcement banner.
+ */
+export const ANNOUNCEMENT_STORAGE_KEY = '@gitbook/announcement';
+/**
+ * The CSS class to hide the announcement banner. Applies to the <html> element.
+ */
+export const ANNOUNCEMENT_CSS_CLASS = 'announcement-hidden';
+/**
+ * The number of days until the announcement banner resets.
+ */
+export const ANNOUNCEMENT_DAYS_TILL_RESET = 7;
diff --git a/packages/gitbook/src/components/Announcement/index.ts b/packages/gitbook/src/components/Announcement/index.ts
new file mode 100644
index 000000000..46a6eead1
--- /dev/null
+++ b/packages/gitbook/src/components/Announcement/index.ts
@@ -0,0 +1,2 @@
+export * from './Announcement';
+export * from './AnnouncementDismissedScript';
diff --git a/packages/gitbook/src/components/Announcement/script.ts b/packages/gitbook/src/components/Announcement/script.ts
new file mode 100644
index 000000000..287e9fc8b
--- /dev/null
+++ b/packages/gitbook/src/components/Announcement/script.ts
@@ -0,0 +1,34 @@
+/**
+ * Read the local storage state for the announcement banner and apply the appropriate CSS class to the <html> element.
+ *
+ * NOTE: this script is stringified and run in the browser, so it must be self-contained and have syntax supported in all browsers.
+ */
+export function checkStorageForDismissedScript(
+    storageKey: string,
+    daysTillReset: number,
+    cssClass: string
+) {
+    let showBanner = true;
+
+    try {
+        const announcementStateStr = window.localStorage.getItem(storageKey);
+        const announcementState = announcementStateStr
+            ? JSON.parse(announcementStateStr)
+            : undefined;
+
+        if (announcementState && !announcementState.visible) {
+            const dismissedAt = announcementState.at;
+            const nowTime = new Date().getTime();
+
+            // Check if enough days have passed since dismissal
+            const daysSinceDismissal = Math.floor((nowTime - dismissedAt) / (1000 * 60 * 60 * 24));
+            if (daysSinceDismissal < daysTillReset) {
+                showBanner = false;
+            }
+        }
+    } catch {}
+
+    if (!showBanner) {
+        document.documentElement.classList.add(cssClass);
+    }
+}
diff --git a/packages/gitbook/src/components/RootLayout/CustomizationRootLayout.tsx b/packages/gitbook/src/components/RootLayout/CustomizationRootLayout.tsx
index 24ba744ee..218dabac0 100644
--- a/packages/gitbook/src/components/RootLayout/CustomizationRootLayout.tsx
+++ b/packages/gitbook/src/components/RootLayout/CustomizationRootLayout.tsx
@@ -34,6 +34,7 @@ import { ClientContexts } from './ClientContexts';
 import '@gitbook/icons/style.css';
 import './globals.css';
 import { GITBOOK_FONTS_URL, GITBOOK_ICONS_TOKEN, GITBOOK_ICONS_URL } from '@v2/lib/env';
+import { AnnouncementDismissedScript } from '../Announcement';
 
 /**
  * Layout shared between the content and the PDF renderer.
@@ -96,6 +97,11 @@ export async function CustomizationRootLayout(props: {
                 {/* Inject custom font @font-face rules */}
                 {fontData.type === 'custom' ? <style>{fontData.fontFaceRules}</style> : null}
 
+                {/* Inject a script to detect if the announcmeent banner has been dismissed */}
+                {'announcement' in customization && customization.announcement?.enabled ? (
+                    <AnnouncementDismissedScript />
+                ) : null}
+
                 <style
                     nonce={
                         //Since I can't get the nonce to work for inline styles, we need to allow unsafe-inline
diff --git a/packages/gitbook/src/components/RootLayout/globals.css b/packages/gitbook/src/components/RootLayout/globals.css
index 9a0fe83f3..71dae7cc6 100644
--- a/packages/gitbook/src/components/RootLayout/globals.css
+++ b/packages/gitbook/src/components/RootLayout/globals.css
@@ -160,3 +160,7 @@ html {
 html.dark {
     color-scheme: dark light;
 }
+
+html.announcement-hidden .announcement-banner {
+    @apply hidden;
+}
diff --git a/packages/gitbook/src/components/SpaceLayout/SpaceLayout.tsx b/packages/gitbook/src/components/SpaceLayout/SpaceLayout.tsx
index 64693f1ea..1932f6b2c 100644
--- a/packages/gitbook/src/components/SpaceLayout/SpaceLayout.tsx
+++ b/packages/gitbook/src/components/SpaceLayout/SpaceLayout.tsx
@@ -13,6 +13,7 @@ import { tcls } from '@/lib/tailwind';
 
 import type { VisitorAuthClaims } from '@/lib/adaptive';
 import { GITBOOK_API_PUBLIC_URL, GITBOOK_APP_URL } from '@v2/lib/env';
+import { Announcement } from '../Announcement';
 import { SpacesDropdown } from '../Header/SpacesDropdown';
 import { InsightsProvider } from '../Insights';
 import { SiteSectionList, encodeClientSiteSections } from '../SiteSections';
@@ -62,6 +63,7 @@ export function SpaceLayout(props: {
                 spaceId={context.space.id}
                 visitorAuthClaims={visitorAuthClaims}
             >
+                <Announcement context={context} />
                 <Header withTopHeader={withTopHeader} context={context} />
                 <div className="scroll-nojump">
                     <div
diff --git a/packages/gitbook/src/components/primitives/StyledLink.tsx b/packages/gitbook/src/components/primitives/StyledLink.tsx
index dcb65b2b9..13b68f0e0 100644
--- a/packages/gitbook/src/components/primitives/StyledLink.tsx
+++ b/packages/gitbook/src/components/primitives/StyledLink.tsx
@@ -2,6 +2,26 @@ import { type ClassValue, tcls } from '@/lib/tailwind';
 
 import { Link, type LinkProps } from '../primitives/Link';
 
+export const linkStyles = [
+    'underline',
+    'decoration-[max(0.07em,1px)]', // Set the underline to be proportional to the font size, with a minimum. The default is too thin.
+    'underline-offset-2',
+    'links-accent:underline-offset-4',
+
+    'links-default:decoration-primary/6',
+    'links-default:text-primary-subtle',
+    'links-default:hover:text-primary-strong',
+    'links-default:contrast-more:text-primary',
+    'links-default:contrast-more:hover:text-primary-strong',
+
+    'links-accent:decoration-primary-subtle',
+    'links-accent:hover:decoration-[3px]',
+    'links-accent:hover:[text-decoration-skip-ink:none]',
+
+    'transition-all',
+    'duration-100',
+];
+
 /**
  * Styled version of Link component.
  */
@@ -9,29 +29,7 @@ export function StyledLink(props: Omit<LinkProps, 'style'> & { style?: ClassValu
     const { style, ...rest } = props;
 
     return (
-        <Link
-            {...rest}
-            className={tcls(
-                'underline',
-                'decoration-[max(0.07em,1px)]', // Set the underline to be proportional to the font size, with a minimum. The default is too thin.
-                'underline-offset-2',
-                'links-accent:underline-offset-4',
-
-                'links-default:decoration-primary/6',
-                'links-default:text-primary-subtle',
-                'links-default:hover:text-primary-strong',
-                'links-default:contrast-more:text-primary',
-                'links-default:contrast-more:hover:text-primary-strong',
-
-                'links-accent:decoration-primary-subtle',
-                'links-accent:hover:decoration-[3px]',
-                'links-accent:hover:[text-decoration-skip-ink:none]',
-
-                'transition-all',
-                'duration-100',
-                style
-            )}
-        >
+        <Link {...rest} className={tcls(linkStyles, style)}>
             {props.children}
         </Link>
     );