diff --git a/.changeset/visitor-country-hostnames-env.md b/.changeset/visitor-country-hostnames-env.md
new file mode 100644
index 000000000..0d2a1a371
--- /dev/null
+++ b/.changeset/visitor-country-hostnames-env.md
@@ -0,0 +1,5 @@
+---
+"gitbook": patch
+---
+
+Read the production hostnames that receive the visitor country from the `GITBOOK_VISITOR_COUNTRY_HOSTNAMES` build-time env variable.
diff --git a/.github/composite/deploy-vercel/action.yaml b/.github/composite/deploy-vercel/action.yaml
index 4fd08e0c5..aeb934fd9 100644
--- a/.github/composite/deploy-vercel/action.yaml
+++ b/.github/composite/deploy-vercel/action.yaml
@@ -78,6 +78,11 @@ runs:
               echo "GITBOOK_DISABLE_INSIGHTS=true" >> .vercel/.env.${{ inputs.environment }}.local
               echo "--- .vercel/.env.${{ inputs.environment }}.local after inject ---"
               cat .vercel/.env.${{ inputs.environment }}.local
+        - name: Inject visitor country hostnames
+          if: ${{ env.GITBOOK_VISITOR_COUNTRY_HOSTNAMES != '' }}
+          shell: bash
+          run: |
+              echo "GITBOOK_VISITOR_COUNTRY_HOSTNAMES=$GITBOOK_VISITOR_COUNTRY_HOSTNAMES" >> .vercel/.env.${{ inputs.environment }}.local
         - name: Inject staging build env vars
           if: ${{ inputs.environment == 'staging' }}
           shell: bash
diff --git a/.github/workflows/deploy-production.yaml b/.github/workflows/deploy-production.yaml
index dcf465a76..471ada6ba 100644
--- a/.github/workflows/deploy-production.yaml
+++ b/.github/workflows/deploy-production.yaml
@@ -10,6 +10,8 @@ jobs:
         environment:
             name: 2v-production
             url: ${{ steps.deploy.outputs.deployment-url }}
+        env:
+            GITBOOK_VISITOR_COUNTRY_HOSTNAMES: ${{ vars.GITBOOK_VISITOR_COUNTRY_HOSTNAMES }}
         outputs:
             deployment-url: ${{ steps.deploy.outputs.deployment-url }}
         steps:
@@ -31,6 +33,8 @@ jobs:
         environment:
             name: 2c-production
             url: ${{ steps.deploy.outputs.deployment-url }}
+        env:
+            GITBOOK_VISITOR_COUNTRY_HOSTNAMES: ${{ vars.GITBOOK_VISITOR_COUNTRY_HOSTNAMES }}
         outputs:
             deployment-url: ${{ steps.deploy.outputs.deployment-url }}
         steps:
diff --git a/packages/gitbook/next.config.mjs b/packages/gitbook/next.config.mjs
index ce1c0113b..6523801da 100644
--- a/packages/gitbook/next.config.mjs
+++ b/packages/gitbook/next.config.mjs
@@ -95,6 +95,7 @@ const nextConfig = {
         GITBOOK_BLOCK_SEARCH_INDEXATION: process.env.GITBOOK_BLOCK_SEARCH_INDEXATION,
         GITBOOK_ALLOW_CUSTOMIZATION_OVERRIDE: process.env.GITBOOK_ALLOW_CUSTOMIZATION_OVERRIDE,
         GITBOOK_DISABLE_INSIGHTS: process.env.GITBOOK_DISABLE_INSIGHTS,
+        GITBOOK_VISITOR_COUNTRY_HOSTNAMES: process.env.GITBOOK_VISITOR_COUNTRY_HOSTNAMES,
         VERCEL_TARGET_ENV: process.env.VERCEL_TARGET_ENV,
 
         // Next.js envs
diff --git a/packages/gitbook/src/lib/visitors.test.ts b/packages/gitbook/src/lib/visitors.test.ts
index 0a583d330..f5e2f3c0b 100644
--- a/packages/gitbook/src/lib/visitors.test.ts
+++ b/packages/gitbook/src/lib/visitors.test.ts
@@ -13,6 +13,7 @@ import {
     getVisitorUnsignedClaims,
     isRevalidationRequest,
     normalizeVisitorURL,
+    parseHostnameList,
     shouldSendVisitorCountry,
 } from './visitors';
 
@@ -674,3 +675,19 @@ describe('shouldSendVisitorCountry', () => {
         }
     );
 });
+
+describe('parseHostnameList', () => {
+    it.each([undefined, '', ' , '])('should return an empty set for %p', (value) => {
+        expect(parseHostnameList(value).size).toBe(0);
+    });
+
+    it('should parse a single entry', () => {
+        expect(parseHostnameList('docs.foo.com')).toEqual(new Set(['docs.foo.com']));
+    });
+
+    it('should trim, lowercase and drop empty entries', () => {
+        expect(parseHostnameList(' Docs.Foo.com , ,bar.io')).toEqual(
+            new Set(['docs.foo.com', 'bar.io'])
+        );
+    });
+});
diff --git a/packages/gitbook/src/lib/visitors.ts b/packages/gitbook/src/lib/visitors.ts
index 3a0186be1..33a7ed937 100644
--- a/packages/gitbook/src/lib/visitors.ts
+++ b/packages/gitbook/src/lib/visitors.ts
@@ -107,15 +107,29 @@ export function getVisitorType(request: {
 }
 
 // Production hostnames for which the visitor country is sent while the feature is rolled out.
-const VISITOR_COUNTRY_HOSTNAMES = new Set<string>([]);
+// Set at build time from a GitHub Actions variable to keep customer hostnames out of the code.
+const VISITOR_COUNTRY_HOSTNAMES = parseHostnameList(process.env.GITBOOK_VISITOR_COUNTRY_HOSTNAMES);
 const VISITOR_COUNTRY_STAGES = new Set(['dev', 'preview', 'staging']);
 
+/**
+ * Parse a comma-separated list of hostnames.
+ */
+export function parseHostnameList(value: string | undefined): Set<string> {
+    return new Set(
+        (value ?? '')
+            .split(',')
+            .map((hostname) => hostname.trim().toLowerCase())
+            .filter(Boolean)
+    );
+}
+
 /**
  * Whether the visitor country should be sent when resolving the site URL.
  */
 export function shouldSendVisitorCountry(hostname: string, stage: string | undefined): boolean {
     return (
-        (!!stage && VISITOR_COUNTRY_STAGES.has(stage)) || VISITOR_COUNTRY_HOSTNAMES.has(hostname)
+        (!!stage && VISITOR_COUNTRY_STAGES.has(stage)) ||
+        VISITOR_COUNTRY_HOSTNAMES.has(hostname.toLowerCase())
     );
 }