diff --git a/.changeset/wise-mails-agree.md b/.changeset/wise-mails-agree.md
new file mode 100644
index 0000000000..1ad08c2ef6
--- /dev/null
+++ b/.changeset/wise-mails-agree.md
@@ -0,0 +1,6 @@
+---
+'@backstage/plugin-notifications-backend': patch
+'@backstage/plugin-notifications-common': minor
+---
+
+Add an optional generic object `metadata` field to `NotificationPayload`. Metadata can be used to store additional unstructured data for the notification and are available to use by processors.
diff --git a/beps/0001-notifications-system/README.md b/beps/0001-notifications-system/README.md
index 03fb224e1c..bfea3115f9 100644
--- a/beps/0001-notifications-system/README.md
+++ b/beps/0001-notifications-system/README.md
@@ -211,10 +211,7 @@ export type NotificationPayload = {
   topic?: string;
   scope?: string;
   icon?: string;
-  metadata?: Array<{
-    type: string;
-    value: JsonValue;
-  }>;
+  metadata?: { [KMetadataKey in string]?: JsonValue };
 };
 
 export type Notification = {
diff --git a/docs/notifications/usage.md b/docs/notifications/usage.md
index 358426dc21..94de585d21 100644
--- a/docs/notifications/usage.md
+++ b/docs/notifications/usage.md
@@ -210,3 +210,68 @@ notificationsApi.getNotification(yourId);
 // or with connection to signals:
 notificationsApi.getNotification(lastSignal.notification_id);
 ```
+
+## Metadata Field
+
+The metadata field is a freeform object that is designed to be used by processors.
+
+### Well-known Notification Metadata Fields
+
+Below are metadata fields that will be commonly used between processors and have defined schematics.
+
+#### backstage.io/body.markdown
+
+```ts
+# Example:
+const payload = {
+  title: 'Entities Require Attention',
+  description: 'Entities: Service A, Service B'
+  metadata: {
+     'backstage.io/body.markdown': `
+        # Entities
+        - Service A
+        - System B
+     `
+  }
+}
+```
+
+This value of this metadata field should be the notification message in markdown format. This allows additional formatting options for processors that support markdown.
+
+### Usage
+
+Below is an example of using the `backstage.io/body.markdown` metadata field in a custom processor.
+
+When sending a notification:
+
+```ts
+notificationService.send({
+  recipients: { type: 'entity', entityRef: 'group/default:team-a' },
+  payload: {
+    title: 'Notification',
+    description: 'Description'
+    metadata: {
+      'backstage.io/body.markdown': `
+        ### Notification
+        Description
+      `,
+    },
+  },
+});
+```
+
+In the processor, you can then use the metadata field accordingly:
+
+```ts
+async postProcess(notification: Notification): Promise<void> {
+  // We suggest you parse the metadata field with a schema, i.e. Zod
+  const parseResult = CustomProcessorMetadataSchema.safeParse(notification.payload.metadata ?? {});
+  const metadata = parseResult.success ? parseResult.data : {};
+
+  customNotificationSender.send({
+    to: getUsers(notification.recipients),
+    subject: notification.payload.title,
+    markdownText: metadata['backstage.io/body.markdown'] ?? notification.payload.description,
+  });
+}
+```
diff --git a/plugins/notifications-backend/src/service/router.test.ts b/plugins/notifications-backend/src/service/router.test.ts
index 6c74fed41c..980762edbc 100644
--- a/plugins/notifications-backend/src/service/router.test.ts
+++ b/plugins/notifications-backend/src/service/router.test.ts
@@ -241,6 +241,9 @@ describe.each(databases.eachSupportedId())('createRouter (%s)', databaseId => {
         },
         payload: {
           title: 'test notification',
+          metadata: {
+            attr: 1,
+          },
         },
       });
 
@@ -253,6 +256,9 @@ describe.each(databases.eachSupportedId())('createRouter (%s)', databaseId => {
           payload: {
             severity: 'normal',
             title: 'test notification',
+            metadata: {
+              attr: 1,
+            },
           },
           user: 'user:default/mock',
         },
diff --git a/plugins/notifications-common/package.json b/plugins/notifications-common/package.json
index 66473d0237..9e1c544ba1 100644
--- a/plugins/notifications-common/package.json
+++ b/plugins/notifications-common/package.json
@@ -40,6 +40,7 @@
   },
   "dependencies": {
     "@backstage/config": "workspace:^",
+    "@backstage/types": "workspace:^",
     "@material-ui/icons": "^4.9.1"
   },
   "devDependencies": {
diff --git a/plugins/notifications-common/report.api.md b/plugins/notifications-common/report.api.md
index 93889b206b..337c41b7b5 100644
--- a/plugins/notifications-common/report.api.md
+++ b/plugins/notifications-common/report.api.md
@@ -4,6 +4,7 @@
 
 ```ts
 import { Config } from '@backstage/config';
+import { JsonValue } from '@backstage/types';
 
 // @public (undocumented)
 export type ChannelSetting = {
@@ -52,6 +53,9 @@ export type NotificationPayload = {
   topic?: string;
   scope?: string;
   icon?: string;
+  metadata?: {
+    [KMetadataKey in string]?: JsonValue;
+  };
 };
 
 // @public (undocumented)
diff --git a/plugins/notifications-common/src/types.ts b/plugins/notifications-common/src/types.ts
index 48f89cbbb4..4e49de79de 100644
--- a/plugins/notifications-common/src/types.ts
+++ b/plugins/notifications-common/src/types.ts
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+import { JsonValue } from '@backstage/types';
+
 /** @public */
 export type NotificationSeverity = 'critical' | 'high' | 'normal' | 'low';
 
@@ -50,6 +52,10 @@ export type NotificationPayload = {
    * Optional notification icon
    */
   icon?: string;
+  /**
+   * Optional additional customizable metadata.
+   */
+  metadata?: { [KMetadataKey in string]?: JsonValue };
 };
 
 /** @public */
diff --git a/yarn.lock b/yarn.lock
index a3334417ab..c3cdc943dd 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5751,6 +5751,7 @@ __metadata:
   dependencies:
     "@backstage/cli": "workspace:^"
     "@backstage/config": "workspace:^"
+    "@backstage/types": "workspace:^"
     "@material-ui/icons": "npm:^4.9.1"
   languageName: unknown
   linkType: soft