diff --git a/README.md b/README.md
index 817a293..28e1fe7 100644
--- a/README.md
+++ b/README.md
@@ -112,6 +112,7 @@ with:
 | `extension-auto-install` | Which extensions to install on startup of LocalStack (application preview) | `None`   | 
 | `github-token`          | Github token used to create PR comments |  |
 | `image-tag`        | Tag of the LocalStack Docker image to use                                        | `latest` |
+| `image-name`       | Full name of the LocalStack Docker image to use (e.g., `my.registry.com/localstack/localstack:latest`). Overrides `image-tag`. | `''`   |
 | `include-preview`          | Whether to include the created Ephemeral Instance URL in the PR comment | `false` |
 | `install-awslocal` | Whether to install the `awslocal` CLI into the build environment                 | `true`   |
 | `lifetime`         | How long an ephemeral instance should live                                       | 30       |
diff --git a/action.yml b/action.yml
index 587adc5..02a8c2e 100644
--- a/action.yml
+++ b/action.yml
@@ -11,6 +11,10 @@ inputs:
     description: 'Tag of the LocalStack Docker image to use'
     required: true
     default: 'latest'
+  image-name:
+    description: 'Full name of the LocalStack Docker image to use (e.g., my.registry.com/localstack/localstack:latest). Overrides image-tag.'
+    required: false
+    default: ''
   install-awslocal:
     description: 'Whether to install the `awslocal` CLI into the environment'
     required: true
@@ -117,6 +121,7 @@ runs:
         with: |-
           {
             "image-tag": ${{ toJSON(inputs.image-tag) }},
+            "image-name": ${{ toJSON(inputs.image-name) }},
             "install-awslocal": ${{ toJSON(inputs.install-awslocal) }},
             "use-pro": ${{ toJSON(inputs.use-pro) }},
             "configuration": ${{ toJSON(inputs.configuration) }},
diff --git a/ephemeral/startup/action.yml b/ephemeral/startup/action.yml
index 5a580b3..1d1f8e4 100644
--- a/ephemeral/startup/action.yml
+++ b/ephemeral/startup/action.yml
@@ -1,4 +1,5 @@
 name: Create PR Preview
+description: 'Creates a preview environment for a pull request.'
 
 inputs:
   github-token:
diff --git a/startup/action.yml b/startup/action.yml
index ec88fd5..88f148f 100644
--- a/startup/action.yml
+++ b/startup/action.yml
@@ -1,10 +1,15 @@
 name: 'Start up Localstack'
+description: 'Starts up LocalStack container'
 
 inputs:
   image-tag:
     description: 'Tag of the LocalStack Docker image to use'
     required: true
     default: 'latest'
+  image-name:
+    description: 'Full name of the LocalStack Docker image to use (e.g., my.registry.com/localstack/localstack:latest). Overrides image-tag.'
+    required: false
+    default: ''
   install-awslocal:
     description: 'Whether to install the `awslocal` CLI into the environment'
     required: true
@@ -60,14 +65,16 @@ runs:
 
     - name: Start LocalStack
       run: |
-        if [ "$USE_PRO" = true ]; then
-          if [ "x$LOCALSTACK_AUTH_TOKEN" = "x" -o "x$LOCALSTACK_API_KEY" = "x" ]; then
-            echo "WARNING: LocalStack API key not detected, please verify your configuration..."
+        if [ -z "$IMAGE_NAME" ]; then
+          if [ "$USE_PRO" = true ]; then
+            if [ "x$LOCALSTACK_AUTH_TOKEN" = "x" -o "x$LOCALSTACK_API_KEY" = "x" ]; then
+              echo "WARNING: LocalStack API key not detected, please verify your configuration..."
+            fi
+            CONFIGURATION="DNS_ADDRESS=127.0.0.1 ${CONFIGURATION}"
+            IMAGE_NAME="localstack/localstack-pro:${IMAGE_TAG}"
+          else
+            IMAGE_NAME="localstack/localstack:${IMAGE_TAG}"
           fi
-          CONFIGURATION="DNS_ADDRESS=127.0.0.1 ${CONFIGURATION}"
-          IMAGE_NAME="${IMAGE_NAME:-localstack/localstack-pro:${IMAGE_TAG}}"
-        else
-          IMAGE_NAME="${IMAGE_NAME:-localstack/localstack:${IMAGE_TAG}}"
         fi
 
         CONFIGURATION="IMAGE_NAME=${IMAGE_NAME} ${CONFIGURATION}"
@@ -82,6 +89,7 @@ runs:
       shell: bash
       env:
         IMAGE_TAG: ${{ inputs.image-tag }}
+        IMAGE_NAME: ${{ inputs.image-name }}
         INSTALL_AWSLOCAL: ${{ inputs.install-awslocal }}
         USE_PRO: ${{ inputs.use-pro }}
         CONFIGURATION: ${{ inputs.configuration }}