diff --git a/aio/firebase.json b/aio/firebase.json
index 752e81bde2..5a8970eef8 100644
--- a/aio/firebase.json
+++ b/aio/firebase.json
@@ -1,5 +1,6 @@
 {
   "hosting": {
+    "target": "aio",
     "public": "dist",
     "cleanUrls": true,
     "redirects": [
diff --git a/aio/scripts/deploy-to-firebase.sh b/aio/scripts/deploy-to-firebase.sh
index dd025e2b78..a6d7ca38a3 100755
--- a/aio/scripts/deploy-to-firebase.sh
+++ b/aio/scripts/deploy-to-firebase.sh
@@ -33,7 +33,7 @@ else
   readonly majorVersionStable=${CI_STABLE_BRANCH%%.*}
 
   # Do not deploy if the major version is not less than the stable branch major version
-  if [[ !( "$majorVersion" -lt "$majorVersionStable" ) ]]; then
+  if (( $majorVersion >= $majorVersionStable )); then
     echo "Skipping deploy of branch \"$CI_BRANCH\" to firebase."
     echo "We only deploy archive branches with the major version less than the stable branch: \"$CI_STABLE_BRANCH\""
     exit 0
@@ -105,9 +105,20 @@ fi
   # Check payload size
   yarn payload-size
 
+
   # Deploy to Firebase
-  yarn firebase use "$projectId" --token "$firebaseToken"
-  yarn firebase deploy --message "Commit: $CI_COMMIT" --non-interactive --token "$firebaseToken"
+
+  # Special case v9-angular-io because its piloting the firebase hosting "multisites" setup
+  # See https://angular-team.atlassian.net/browse/DEV-125 for more info.
+  if [[ "$projectId" == "v9-angular-io" ]]; then
+    yarn firebase use aio-staging --token "$firebaseToken"
+    yarn firebase target:apply hosting aio $projectId --token "$firebaseToken"
+    yarn firebase deploy --only hosting:aio --message "Commit: $CI_COMMIT" --non-interactive --token "$firebaseToken"
+  elif
+    yarn firebase use "$projectId" --token "$firebaseToken"
+    yarn firebase deploy --message "Commit: $CI_COMMIT" --non-interactive --token "$firebaseToken"
+  fi
+
 
   # Run PWA-score tests
   yarn test-pwa-score "$deployedUrl" "$CI_AIO_MIN_PWA_SCORE"
diff --git a/aio/scripts/deploy-to-firebase.test.sh b/aio/scripts/deploy-to-firebase.test.sh
index 575cab280d..37b4e3d832 100755
--- a/aio/scripts/deploy-to-firebase.test.sh
+++ b/aio/scripts/deploy-to-firebase.test.sh
@@ -143,6 +143,31 @@ Deployment URL    : https://v2.angular.io/"
   check "$actual" "$expected"
 )
 
+(
+  echo ===== archive - v9-angular-io multisite special case - deploy success
+  actual=$(
+    export BASH_ENV=/dev/null
+    export CI_REPO_OWNER=angular
+    export CI_REPO_NAME=angular
+    export CI_PULL_REQUEST=false
+    export CI_BRANCH=9.1.x
+    export CI_STABLE_BRANCH=10.0.x
+    export CI_COMMIT=$(git ls-remote origin 9.1.x | cut -c1-40)
+    export CI_SECRET_AIO_DEPLOY_FIREBASE_TOKEN=XXXXX
+    $deployToFirebaseDryRun
+  )
+  expected="Git branch        : 9.1.x
+Build/deploy mode : archive
+Firebase project  : v9-angular-io
+Deployment URL    : https://v9.angular.io/"
+  # TODO: This test incorrectly expects the Firebase project to be v9-angular-io.
+  #       v9-angular-io is a "multisites" project currently within the aio-staging project
+  #       This setup is temporary and was created in order to deploy v9.angular.io without
+  #       disruptions.
+  #       See https://angular-team.atlassian.net/browse/DEV-125 for more info.
+  check "$actual" "$expected"
+)
+
 (
   echo ===== archive - skip deploy - commit not HEAD
   actual=$(