diff --git a/README.md b/README.md
index aaa564e..794b23f 100644
--- a/README.md
+++ b/README.md
@@ -181,6 +181,7 @@ Available targets:
 | <a name="input_context"></a> [context](#input\_context) | Single object for setting entire context at once.<br>See description of individual variables for details.<br>Leave string and numeric variables as `null` to use default value.<br>Individual variable settings (non-null) override settings in context object,<br>except for attributes, tags, and additional\_tag\_map, which are merged. | `any` | <pre>{<br>  "additional_tag_map": {},<br>  "attributes": [],<br>  "delimiter": null,<br>  "descriptor_formats": {},<br>  "enabled": true,<br>  "environment": null,<br>  "id_length_limit": null,<br>  "label_key_case": null,<br>  "label_order": [],<br>  "label_value_case": null,<br>  "labels_as_tags": [<br>    "unset"<br>  ],<br>  "name": null,<br>  "namespace": null,<br>  "regex_replace_chars": null,<br>  "stage": null,<br>  "tags": {},<br>  "tenant": null<br>}</pre> | no |
 | <a name="input_custom_response_body"></a> [custom\_response\_body](#input\_custom\_response\_body) | Defines custom response bodies that can be referenced by custom\_response actions.<br>The map keys are used as the `key` attribute which is a unique key identifying the custom response body.<br>content:<br>  Payload of the custom response.<br>  The response body can be plain text, HTML or JSON and cannot exceed 4KB in size.<br>content\_type:<br>  Content Type of Response Body.<br>  Valid values are `TEXT_PLAIN`, `TEXT_HTML`, or `APPLICATION_JSON`. | <pre>map(object({<br>    content      = string<br>    content_type = string<br>  }))</pre> | `{}` | no |
 | <a name="input_default_action"></a> [default\_action](#input\_default\_action) | Specifies that AWS WAF should allow requests by default. Possible values: `allow`, `block`. | `string` | `"block"` | no |
+| <a name="input_default_block_custom_response_body_key"></a> [default\_block\_custom\_response\_body\_key](#input\_default\_block\_custom\_response\_body\_key) | References the default response body that you want AWS WAF to return to the web request client.<br>This must reference a key defined in a custom\_response\_body block of this resource.<br>Only takes effect if default\_action is set to `block`. | `string` | `null` | no |
 | <a name="input_default_block_response"></a> [default\_block\_response](#input\_default\_block\_response) | A HTTP response code that is sent when default block action is used. Only takes effect if default\_action is set to `block`. | `string` | `null` | no |
 | <a name="input_delimiter"></a> [delimiter](#input\_delimiter) | Delimiter to be used between ID elements.<br>Defaults to `-` (hyphen). Set to `""` to use no delimiter at all. | `string` | `null` | no |
 | <a name="input_description"></a> [description](#input\_description) | A friendly description of the WebACL. | `string` | `"Managed by Terraform"` | no |
diff --git a/docs/terraform.md b/docs/terraform.md
index f82f700..c0a79bd 100644
--- a/docs/terraform.md
+++ b/docs/terraform.md
@@ -39,6 +39,7 @@
 | <a name="input_context"></a> [context](#input\_context) | Single object for setting entire context at once.<br>See description of individual variables for details.<br>Leave string and numeric variables as `null` to use default value.<br>Individual variable settings (non-null) override settings in context object,<br>except for attributes, tags, and additional\_tag\_map, which are merged. | `any` | <pre>{<br>  "additional_tag_map": {},<br>  "attributes": [],<br>  "delimiter": null,<br>  "descriptor_formats": {},<br>  "enabled": true,<br>  "environment": null,<br>  "id_length_limit": null,<br>  "label_key_case": null,<br>  "label_order": [],<br>  "label_value_case": null,<br>  "labels_as_tags": [<br>    "unset"<br>  ],<br>  "name": null,<br>  "namespace": null,<br>  "regex_replace_chars": null,<br>  "stage": null,<br>  "tags": {},<br>  "tenant": null<br>}</pre> | no |
 | <a name="input_custom_response_body"></a> [custom\_response\_body](#input\_custom\_response\_body) | Defines custom response bodies that can be referenced by custom\_response actions.<br>The map keys are used as the `key` attribute which is a unique key identifying the custom response body.<br>content:<br>  Payload of the custom response.<br>  The response body can be plain text, HTML or JSON and cannot exceed 4KB in size.<br>content\_type:<br>  Content Type of Response Body.<br>  Valid values are `TEXT_PLAIN`, `TEXT_HTML`, or `APPLICATION_JSON`. | <pre>map(object({<br>    content      = string<br>    content_type = string<br>  }))</pre> | `{}` | no |
 | <a name="input_default_action"></a> [default\_action](#input\_default\_action) | Specifies that AWS WAF should allow requests by default. Possible values: `allow`, `block`. | `string` | `"block"` | no |
+| <a name="input_default_block_custom_response_body_key"></a> [default\_block\_custom\_response\_body\_key](#input\_default\_block\_custom\_response\_body\_key) | References the default response body that you want AWS WAF to return to the web request client.<br>This must reference a key defined in a custom\_response\_body block of this resource.<br>Only takes effect if default\_action is set to `block`. | `string` | `null` | no |
 | <a name="input_default_block_response"></a> [default\_block\_response](#input\_default\_block\_response) | A HTTP response code that is sent when default block action is used. Only takes effect if default\_action is set to `block`. | `string` | `null` | no |
 | <a name="input_delimiter"></a> [delimiter](#input\_delimiter) | Delimiter to be used between ID elements.<br>Defaults to `-` (hyphen). Set to `""` to use no delimiter at all. | `string` | `null` | no |
 | <a name="input_description"></a> [description](#input\_description) | A friendly description of the WebACL. | `string` | `"Managed by Terraform"` | no |
diff --git a/rules.tf b/rules.tf
index 74522c8..459f147 100644
--- a/rules.tf
+++ b/rules.tf
@@ -88,6 +88,8 @@ locals {
       rule.action,
     ) => rule
   } : {}
+
+  default_custom_response_body_key = var.default_block_custom_response_body_key != null ? contains(keys(var.custom_response_body), var.default_block_custom_response_body_key) ? var.default_block_custom_response_body_key : null : null
 }
 
 resource "aws_wafv2_web_acl" "default" {
@@ -111,7 +113,8 @@ resource "aws_wafv2_web_acl" "default" {
         dynamic "custom_response" {
           for_each = var.default_block_response != null ? [true] : []
           content {
-            response_code = var.default_block_response
+            response_code            = var.default_block_response
+            custom_response_body_key = local.default_custom_response_body_key
           }
         }
       }
diff --git a/variables.tf b/variables.tf
index d5384be..3d5e991 100644
--- a/variables.tf
+++ b/variables.tf
@@ -1047,3 +1047,14 @@ variable "default_block_response" {
   DOC
   nullable    = true
 }
+
+variable "default_block_custom_response_body_key" {
+  type        = string
+  default     = null
+  description = <<-DOC
+    References the default response body that you want AWS WAF to return to the web request client.
+    This must reference a key defined in a custom_response_body block of this resource.
+    Only takes effect if default_action is set to `block`.
+  DOC
+  nullable    = true
+}