diff --git a/.docker/database-services.yml b/.docker/database-services.yml
index a3176b5..de29147 100644
--- a/.docker/database-services.yml
+++ b/.docker/database-services.yml
@@ -17,6 +17,34 @@ services:
       - MYSQL_DATABASE=${MYSQL_DATABASE:-nextcloud}
       - MYSQL_USER=${MYSQL_USER:-nextcloud}
       - MYSQL_PASSWORD=${MYSQL_PASSWORD:-nextcloud}
+  mariadb106:
+    image: mariadb:10.6.28@sha256:23616f0bd3aff922f4dea4130f1d0a09f3571d20b7b36c8f49840672dc309e8c
+    volumes:
+      - ${WORKER_VOLUMES_DIR:-../volumes}/mariadb/data:/var/lib/mysql
+    ports:
+      - target: 3306
+        published: "3306-3325"
+        host_ip: ${MARIADB_IP_BIND:-127.0.0.1}
+    environment:
+      - TZ=${TZ:-CET}
+      - MARIADB_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD:-root}
+      - MARIADB_DATABASE=${MYSQL_DATABASE:-nextcloud}
+      - MARIADB_USER=${MYSQL_USER:-nextcloud}
+      - MARIADB_PASSWORD=${MYSQL_PASSWORD:-nextcloud}
+  mariadb1011:
+    image: mariadb:10.11.19@sha256:07c0aaff7396b74cb7975cba78257178d188e30f531a5db2b617c48beef13c41
+    volumes:
+      - ${WORKER_VOLUMES_DIR:-../volumes}/mariadb/data:/var/lib/mysql
+    ports:
+      - target: 3306
+        published: "3306-3325"
+        host_ip: ${MARIADB_IP_BIND:-127.0.0.1}
+    environment:
+      - TZ=${TZ:-CET}
+      - MARIADB_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD:-root}
+      - MARIADB_DATABASE=${MYSQL_DATABASE:-nextcloud}
+      - MARIADB_USER=${MYSQL_USER:-nextcloud}
+      - MARIADB_PASSWORD=${MYSQL_PASSWORD:-nextcloud}
   pgsql:
     image: postgres:13-alpine@sha256:fb9065b6e3e213bdc07edd372a5b2a26245840b7fb65d1fd8b6700106d51805c
     volumes:
diff --git a/.docker/scripts/nextcloud-entrypoint.sh b/.docker/scripts/nextcloud-entrypoint.sh
index c566b14..29ea2d1 100644
--- a/.docker/scripts/nextcloud-entrypoint.sh
+++ b/.docker/scripts/nextcloud-entrypoint.sh
@@ -43,7 +43,7 @@ fi
 # Set configurations, if needed
 if [[ ! -f "config/config.php" && ${AUTOINSTALL} -eq 1 ]]; then
     echo "⌛️ Starting installation ..."
-    if [[ "${db_type}" == 'mysql' ]]; then
+    if [[ "${db_type}" == 'mysql' || "${db_type}" == 'mariadb' ]]; then
         occ maintenance:install --verbose --database="${db_driver}" --database-name="${MYSQL_DATABASE}" --database-host="${db_host}" --database-port= --database-user="${MYSQL_USER}" --database-pass="${MYSQL_PASSWORD}" --admin-user="${NEXTCLOUD_ADMIN_USER}" --admin-pass="${NEXTCLOUD_ADMIN_PASSWORD}" --admin-email="${NEXTCLOUD_ADMIN_EMAIL}"
         install_cmd_status=$?
     elif [[ "${db_type}" == 'pgsql' ]]; then
@@ -61,6 +61,8 @@ if [[ ! -f "config/config.php" && ${AUTOINSTALL} -eq 1 ]]; then
         db_reset_hint="volumes/nextcloud/config and volumes/nextcloud/data"
         if [[ "${db_type}" == 'mysql' ]]; then
             db_reset_hint="volumes/mysql/data, ${db_reset_hint}"
+        elif [[ "${db_type}" == 'mariadb' ]]; then
+            db_reset_hint="volumes/mariadb/data, ${db_reset_hint}"
         elif [[ "${db_type}" == 'pgsql' ]]; then
             db_reset_hint="volumes/postgres/data, ${db_reset_hint}"
         fi
diff --git a/.docker/scripts/wait-for-db.php b/.docker/scripts/wait-for-db.php
index e5eebc9..372aa5a 100644
--- a/.docker/scripts/wait-for-db.php
+++ b/.docker/scripts/wait-for-db.php
@@ -8,7 +8,7 @@
 
 function dbIsUp(string $dbName): bool {
     try {
-        if ($GLOBALS['dbType'] === 'mysql') {
+        if ($GLOBALS['dbType'] === 'mysql' || $GLOBALS['dbType'] === 'mariadb') {
             $dsn = 'mysql:dbname='.getenv('MYSQL_DATABASE').';host='.$GLOBALS['dbHost'];
             new PDO($dsn, getenv('MYSQL_USER'), getenv('MYSQL_PASSWORD'));
         } elseif ($GLOBALS['dbType'] === 'pgsql') {
diff --git a/.github/workflows/proxy-tests.yml b/.github/workflows/proxy-tests.yml
index 64b49f5..62a893a 100644
--- a/.github/workflows/proxy-tests.yml
+++ b/.github/workflows/proxy-tests.yml
@@ -64,10 +64,10 @@ jobs:
           DB_TYPE=sqlite sh ./dev-worker sqlite-b exec occ status | grep -q 'installed: true'
       - name: Verify SQLite worker state isolation
         run: |
-          DB_TYPE=sqlite sh ./dev-worker sqlite-a exec occ config:system:set worker_probe --value alpha
-          DB_TYPE=sqlite sh ./dev-worker sqlite-b exec occ config:system:set worker_probe --value beta
-          alpha="$(DB_TYPE=sqlite sh ./dev-worker sqlite-a exec occ config:system:get worker_probe | tail -n 1)"
-          beta="$(DB_TYPE=sqlite sh ./dev-worker sqlite-b exec occ config:system:get worker_probe | tail -n 1)"
+          DB_TYPE=sqlite sh ./dev-worker sqlite-a exec sh -c 'printf alpha > /var/www/html/data/worker-probe'
+          DB_TYPE=sqlite sh ./dev-worker sqlite-b exec sh -c 'printf beta > /var/www/html/data/worker-probe'
+          alpha="$(DB_TYPE=sqlite sh ./dev-worker sqlite-a exec cat /var/www/html/data/worker-probe)"
+          beta="$(DB_TYPE=sqlite sh ./dev-worker sqlite-b exec cat /var/www/html/data/worker-probe)"
           printf 'sqlite-a worker_probe=%s\nsqlite-b worker_probe=%s\n' "$alpha" "$beta"
           test "$alpha" = alpha
           test "$beta" = beta
@@ -88,3 +88,70 @@ jobs:
         run: |
           DB_TYPE=sqlite sh ./dev-worker sqlite-a destroy || true
           DB_TYPE=sqlite sh ./dev-worker sqlite-b destroy || true
+
+  mariadb-worker:
+    name: MariaDB ${{ matrix.mariadb }} worker integration
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    strategy:
+      fail-fast: false
+      matrix:
+        mariadb: ['10.6', '10.11']
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+      - name: Build PHP 8.3 development image
+        run: docker build -f .docker/Dockerfile.php83 -t ghcr.io/librecodecoop/nextcloud-dev-php83:latest .docker
+      - name: Start MariaDB worker
+        env:
+          MARIADB_VERSION: ${{ matrix.mariadb }}
+          DB_SQL_MODE: ONLY_FULL_GROUP_BY
+        run: |
+          worker="maria-${MARIADB_VERSION//./-}"
+          DB_TYPE=mariadb sh ./dev-worker "$worker" up
+      - name: Verify MariaDB version and SQL mode
+        env:
+          MARIADB_VERSION: ${{ matrix.mariadb }}
+          DB_SQL_MODE: ONLY_FULL_GROUP_BY
+        run: |
+          worker="maria-${MARIADB_VERSION//./-}"
+          version="$(DB_TYPE=mariadb sh ./dev-worker "$worker" db-exec mariadb -uroot -proot -Nse 'SELECT VERSION()')"
+          case "$version" in
+            "$MARIADB_VERSION".*) ;;
+            *) echo "Unexpected MariaDB version: $version" >&2; exit 1 ;;
+          esac
+          DB_TYPE=mariadb sh ./dev-worker "$worker" db-exec mariadb -uroot -proot -Nse 'SELECT @@GLOBAL.sql_mode' | grep -q 'ONLY_FULL_GROUP_BY'
+          DB_TYPE=mariadb sh ./dev-worker "$worker" status | grep -q 'installed: true'
+      - name: Verify two-worker isolation
+        if: matrix.mariadb == '10.11'
+        env:
+          MARIADB_VERSION: ${{ matrix.mariadb }}
+          DB_SQL_MODE: ONLY_FULL_GROUP_BY
+        run: |
+          DB_TYPE=mariadb sh ./dev-worker maria-peer up
+          DB_TYPE=mariadb sh ./dev-worker maria-10-11 exec sh -c 'printf alpha > /var/www/html/data/worker-probe'
+          DB_TYPE=mariadb sh ./dev-worker maria-peer exec sh -c 'printf beta > /var/www/html/data/worker-probe'
+          alpha="$(DB_TYPE=mariadb sh ./dev-worker maria-10-11 exec cat /var/www/html/data/worker-probe)"
+          beta="$(DB_TYPE=mariadb sh ./dev-worker maria-peer exec cat /var/www/html/data/worker-probe)"
+          printf 'maria-10-11 worker_probe=%s\nmaria-peer worker_probe=%s\n' "$alpha" "$beta"
+          test "$alpha" = alpha
+          test "$beta" = beta
+      - name: Collect worker logs
+        if: failure()
+        env:
+          MARIADB_VERSION: ${{ matrix.mariadb }}
+        run: |
+          worker="maria-${MARIADB_VERSION//./-}"
+          DB_TYPE=mariadb sh ./dev-worker "$worker" logs || true
+          if [ "$MARIADB_VERSION" = 10.11 ]; then
+            DB_TYPE=mariadb sh ./dev-worker maria-peer logs || true
+          fi
+      - name: Destroy workers
+        if: always()
+        env:
+          MARIADB_VERSION: ${{ matrix.mariadb }}
+        run: |
+          worker="maria-${MARIADB_VERSION//./-}"
+          DB_TYPE=mariadb sh ./dev-worker "$worker" destroy || true
+          if [ "$MARIADB_VERSION" = 10.11 ]; then
+            DB_TYPE=mariadb sh ./dev-worker maria-peer destroy || true
+          fi
diff --git a/dev-worker b/dev-worker
index 5dd4504..2813185 100644
--- a/dev-worker
+++ b/dev-worker
@@ -14,11 +14,14 @@ Commands:
   logs               Print worker logs
   config             Render the resolved Compose configuration
   status             Run occ status in the worker
+  db-exec <command...> Run a command in the selected database container
   destroy            Stop the worker and remove only its mutable state
 
 Environment:
-  DB_TYPE=sqlite|mysql|pgsql Database backend
+  DB_TYPE=sqlite|mysql|mariadb|pgsql Database backend
   DB_HOST=<hostname>        Connection hostname (defaults to DB_TYPE)
+  MARIADB_VERSION=10.6|10.11 MariaDB series (default: 10.11)
+  DB_SQL_MODE=<modes>        Optional global SQL mode for MySQL-compatible backends
   PHP_VERSION=<version>     Existing PHP image selector
   VERSION_NEXTCLOUD=<ref>   Existing Nextcloud ref selector
   WORKER_READY_TIMEOUT=180  Seconds to wait for a clean installation
@@ -53,11 +56,7 @@ repo_root="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"
 db_type="${DB_TYPE:-mysql}"
 
 case "$db_type" in
-	sqlite|mysql|pgsql) ;;
-	mariadb)
-		echo "DB_TYPE=$db_type is reserved by the worker contract but is not implemented yet." >&2
-		exit 3
-		;;
+	sqlite|mysql|mariadb|pgsql) ;;
 	*)
 		echo "Unsupported DB_TYPE: $db_type" >&2
 		exit 2
@@ -74,6 +73,17 @@ export DB_HOST="${DB_HOST:-$db_type}"
 if [ "$db_type" = "sqlite" ]; then
 	export DB_SERVICE_TYPE=mysql
 	export DB_DRIVER=sqlite
+elif [ "$db_type" = "mariadb" ]; then
+	mariadb_version="${MARIADB_VERSION:-10.11}"
+	case "$mariadb_version" in
+		10.6) export DB_SERVICE_TYPE=mariadb106 ;;
+		10.11) export DB_SERVICE_TYPE=mariadb1011 ;;
+		*)
+			echo "Unsupported MARIADB_VERSION: $mariadb_version (supported: 10.6, 10.11)" >&2
+			exit 2
+			;;
+	esac
+	export DB_DRIVER=mysql
 else
 	export DB_SERVICE_TYPE="${DB_SERVICE_TYPE:-$db_type}"
 fi
@@ -82,6 +92,26 @@ compose() {
 	docker compose --project-directory "$repo_root" --file "$repo_root/docker-compose.yml" "$@"
 }
 
+wait_for_mariadb() {
+	timeout="${WORKER_READY_TIMEOUT:-180}"
+	started="$(date +%s)"
+
+	while :; do
+		if compose exec -T database mariadb-admin ping -h 127.0.0.1 -uroot -p"${MYSQL_ROOT_PASSWORD:-root}" --silent >/dev/null 2>&1; then
+			return 0
+		fi
+
+		now="$(date +%s)"
+		if [ $((now - started)) -ge "$timeout" ]; then
+			echo "MariaDB for worker $worker_id did not become ready within ${timeout}s." >&2
+			compose logs --no-color database >&2 || true
+			return 1
+		fi
+
+		sleep 1
+	done
+}
+
 wait_until_ready() {
 	timeout="${WORKER_READY_TIMEOUT:-180}"
 	started="$(date +%s)"
@@ -107,6 +137,16 @@ case "$command" in
 		mkdir -p "$worker_volumes_dir"
 		if [ "$db_type" = "sqlite" ]; then
 			compose up -d nextcloud nginx proxy-coordinator mailpit redis
+		elif [ "$db_type" = "mariadb" ]; then
+			compose up -d database
+			wait_for_mariadb
+			if [ -n "${DB_SQL_MODE:-}" ]; then
+				case "${DB_SQL_MODE}" in
+					*[!A-Z0-9_,]*) echo "DB_SQL_MODE contains unsupported characters" >&2; exit 2 ;;
+				esac
+				compose exec -T database mariadb -uroot -p"${MYSQL_ROOT_PASSWORD:-root}" -e "SET GLOBAL sql_mode='${DB_SQL_MODE}'"
+			fi
+			compose up -d
 		else
 			compose up -d
 		fi
@@ -129,6 +169,17 @@ case "$command" in
 	status)
 		compose exec -T nextcloud occ status
 		;;
+	db-exec)
+		[ "$db_type" != "sqlite" ] || {
+			echo "SQLite workers do not have a database container" >&2
+			exit 3
+		}
+		[ "$#" -gt 0 ] || {
+			echo "db-exec requires a command" >&2
+			exit 2
+		}
+		compose exec -T database "$@"
+		;;
 	destroy)
 		compose down --remove-orphans
 		# Mutable bind mounts contain files created by container UIDs. Clean the
diff --git a/docs/advanced-setup.md b/docs/advanced-setup.md
index 2ff87dc..dbddf12 100644
--- a/docs/advanced-setup.md
+++ b/docs/advanced-setup.md
@@ -35,6 +35,7 @@ The currently implemented backends are:
 
 - `sqlite`
 - `mysql` (default)
+- `mariadb`
 - `pgsql`
 
 To use PostgreSQL:
@@ -78,8 +79,20 @@ DB_TYPE=sqlite sh ./dev-worker sqlite-a status
 DB_TYPE=sqlite sh ./dev-worker sqlite-a destroy
 ```
 
-MariaDB remains reserved by the `DB_TYPE` contract until its dedicated
-backend implementation lands.
+MariaDB workers support the 10.6 and 10.11 series without editing Compose YAML:
+
+```bash
+DB_TYPE=mariadb MARIADB_VERSION=10.6 sh ./dev-worker maria106 up
+DB_TYPE=mariadb MARIADB_VERSION=10.11 sh ./dev-worker maria1011 up
+```
+
+The worker maps each supported series to a pinned image. Use `DB_SQL_MODE` to
+request a deterministic global SQL mode when a test suite needs one:
+
+```bash
+DB_TYPE=mariadb MARIADB_VERSION=10.11 DB_SQL_MODE=ONLY_FULL_GROUP_BY \
+  sh ./dev-worker maria-full-group-by up
+```
 
 ## Optional services
 
diff --git a/tests/worker/contract.bats b/tests/worker/contract.bats
index 74574fc..668074f 100644
--- a/tests/worker/contract.bats
+++ b/tests/worker/contract.bats
@@ -49,10 +49,24 @@ setup() {
 	[[ "$output" == *"DB_DRIVER: sqlite"* ]]
 }
 
-@test "MariaDB remains reserved for its dedicated implementation" {
-	run env DB_TYPE=mariadb sh "$WORKER" mariadb config
-	[ "$status" -eq 3 ]
-	[[ "$output" == *"not implemented yet"* ]]
+@test "MariaDB 10.6 selects the pinned 10.6 service" {
+	run env DB_TYPE=mariadb MARIADB_VERSION=10.6 sh "$WORKER" maria106 config
+	[ "$status" -eq 0 ]
+	[[ "$output" == *"mariadb:10.6.28@sha256:23616f0bd3aff922f4dea4130f1d0a09f3571d20b7b36c8f49840672dc309e8c"* ]]
+	[[ "$output" == *"DB_TYPE: mariadb"* ]]
+	[[ "$output" == *"DB_DRIVER: mysql"* ]]
+}
+
+@test "MariaDB 10.11 selects the pinned 10.11 service" {
+	run env DB_TYPE=mariadb MARIADB_VERSION=10.11 sh "$WORKER" maria1011 config
+	[ "$status" -eq 0 ]
+	[[ "$output" == *"mariadb:10.11.19@sha256:07c0aaff7396b74cb7975cba78257178d188e30f531a5db2b617c48beef13c41"* ]]
+}
+
+@test "unsupported MariaDB versions fail before startup" {
+	run env DB_TYPE=mariadb MARIADB_VERSION=11.4 sh "$WORKER" maria114 config
+	[ "$status" -eq 2 ]
+	[[ "$output" == *"Unsupported MARIADB_VERSION"* ]]
 }
 
 @test "supported PHP images install PDO SQLite" {