diff --git a/apps/api/src/api/application-api.ts b/apps/api/src/api/application-api.ts
index 42b47c2a..acab3c97 100644
--- a/apps/api/src/api/application-api.ts
+++ b/apps/api/src/api/application-api.ts
@@ -17,13 +17,14 @@
  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-import { ApplicationStates } from '@pcgl-daco/data-model/src/types.js';
+import { ApplicationStates, ApproveApplication } from '@pcgl-daco/data-model/src/types.js';
 
 import { getDbInstance } from '@/db/index.js';
 import { ApplicationListRequest } from '@/routes/types.js';
 import applicationService from '@/service/application-service.js';
 import { type ApplicationContentUpdates, type ApplicationService } from '@/service/types.js';
 import { failure } from '@/utils/results.js';
+import { ApplicationStateManager } from './states.js';
 
 /**
  * Creates a new application and returns the created data.
@@ -105,3 +106,62 @@ export const getApplicationById = async ({ applicationId }: { applicationId: num
 
 	return result;
 };
+
+export const approveApplication = async ({
+	applicationId,
+	approverId,
+}: ApproveApplication): Promise<{
+	success: boolean;
+	message?: string;
+	errors?: string | Error;
+	data?: any;
+}> => {
+	try {
+		// Fetch application
+		const database = getDbInstance();
+		const service: ApplicationService = applicationService(database);
+		const result = await service.getApplicationById({ id: applicationId });
+
+		if (!result.success) {
+			return {
+				success: false,
+				message: 'Application not found.',
+				errors: 'ApplicationNotFound',
+			};
+		}
+
+		const application = result.data;
+
+		const appStateManager = new ApplicationStateManager(application);
+
+		if (appStateManager.state === ApplicationStates.APPROVED) {
+			return {
+				success: false,
+				message: 'Application is already approved.',
+				errors: 'ApprovalConflict',
+			};
+		}
+
+		const approvalResult = await appStateManager.approveDacReview();
+		if (!approvalResult.success) {
+			return {
+				success: false,
+				message: 'Failed to approve application.',
+				errors: 'StateTransitionError',
+			};
+		}
+
+		const update = { state: appStateManager.state, approved_at: new Date() };
+		const updatedResult = await service.findOneAndUpdate({ id: applicationId, update });
+
+		return {
+			success: true,
+			data: updatedResult,
+		};
+	} catch (error) {
+		const message = `Unable to approve application with id: ${applicationId}`;
+		console.error(message);
+		console.error(error);
+		return failure(message, error);
+	}
+};
diff --git a/apps/api/src/resources/swagger.yaml b/apps/api/src/resources/swagger.yaml
index 910cbd7e..bfeea9fa 100644
--- a/apps/api/src/resources/swagger.yaml
+++ b/apps/api/src/resources/swagger.yaml
@@ -196,6 +196,43 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/ApplicationRecord'
+  /applications/approve:
+    post:
+      tags:
+        - Applications
+      summary: Approve an application.
+      requestBody:
+        description: Request body containing approval details.
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/requests/ApproveApplication'
+    responses:
+      '200':
+        description: Application successfully approved.
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Applications'
+      '400':
+        description: Invalid request - missing or invalid approval data.
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/responses/ClientErrors'
+      '404':
+        description: Application not found.
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/responses/ClientErrors'
+      '500':
+        description: Server error - Unable to process approval.
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/responses/ServerErrors'
 
 components:
   schemas:
@@ -371,6 +408,19 @@ components:
           type: object
           $ref: '#/components/schemas/ApplicationContents'
 
+    ApproveApplication:
+      type: object
+      required:
+        - applicantId
+        - applicationId
+      properties:
+        applicantId:
+          type: number
+          description: The id of the Applicant
+        applicationId:
+          description: The id of the Application
+          type: number
+
   responses:
     ClientErrors:
       type: object
diff --git a/apps/api/src/routes/application-router.ts b/apps/api/src/routes/application-router.ts
index 61c5e172..5c378ba2 100644
--- a/apps/api/src/routes/application-router.ts
+++ b/apps/api/src/routes/application-router.ts
@@ -20,7 +20,13 @@
 import bodyParser from 'body-parser';
 import express, { Request } from 'express';
 
-import { createApplication, editApplication, getAllApplications, getApplicationById } from '@/api/application-api.js';
+import {
+	approveApplication,
+	createApplication,
+	editApplication,
+	getAllApplications,
+	getApplicationById,
+} from '@/api/application-api.js';
 
 const applicationRouter = express.Router();
 const jsonParser = bodyParser.json();
@@ -135,4 +141,73 @@ applicationRouter.get(
 	},
 );
 
+applicationRouter.post('/applications/approve', jsonParser, async (req, res) => {
+	const { applicationId, approverId }: { applicationId?: number; approverId?: number } = req.body;
+
+	if (typeof applicationId !== 'number' || typeof approverId !== 'number') {
+		res.status(400).send({
+			message: 'Invalid request. Both applicationId and approverId are required and must be numbers.',
+			errors: 'MissingOrInvalidParameters',
+		});
+		return;
+	}
+
+	// Validate input
+	if (!applicationId || !approverId) {
+		res.status(400).send({
+			message: 'Invalid request. Both applicationId and approverId are required.',
+			errors: 'MissingParameters',
+		});
+	}
+
+	try {
+		// Call the service function
+		const result = await approveApplication({ applicationId, approverId });
+
+		if (result.success) {
+			res.status(200).send({
+				message: 'Application approved successfully.',
+				data: result.data,
+			});
+		}
+
+		let status = 200;
+		let message = 'Application approved successfully.';
+		let errors = null;
+
+		if (!result.success) {
+			// Set appropriate error details
+			switch (result.errors) {
+				case 'ApplicationNotFound':
+					status = 404;
+					message = result.message || 'Application not found.';
+					errors = result.errors;
+					break;
+				case 'ApprovalConflict':
+					status = 409;
+					message = result.message || 'Approval conflict detected.';
+					errors = result.errors;
+					break;
+				case 'InvalidState':
+					status = 400;
+					message = result.message || 'Invalid application state.';
+					errors = result.errors;
+					break;
+				default:
+					status = 500;
+					message = 'An unexpected error occurred.';
+					errors = result.errors;
+			}
+		}
+
+		// Send response
+		res.status(status).send({ message, errors, data: result.success ? result.data : undefined });
+	} catch (error) {
+		res.status(500).send({
+			message: 'Internal server error.',
+			errors: String(error),
+		});
+	}
+});
+
 export default applicationRouter;
diff --git a/packages/data-model/src/types.ts b/packages/data-model/src/types.ts
index 1a7267da..d77ac912 100644
--- a/packages/data-model/src/types.ts
+++ b/packages/data-model/src/types.ts
@@ -223,3 +223,8 @@ export type Application = {
 	expires_at: Date;
 	contents: ApplicationContents;
 };
+
+export type ApproveApplication = {
+	applicationId: number; // The ID of the application to be approved
+	approverId: number; // The ID of the user approving the application
+};