diff --git a/src/routes/v2/authenticated/review.ts b/src/routes/v2/authenticated/review.ts
index 37415f269..b0cb82e15 100644
--- a/src/routes/v2/authenticated/review.ts
+++ b/src/routes/v2/authenticated/review.ts
@@ -295,6 +295,70 @@ export class ReviewsRouter {
     return res.status(200).json()
   }
 
+  markReviewRequestAsViewed: RequestHandler<
+    { siteName: string; requestId: number },
+    string | ResponseErrorBody,
+    never,
+    unknown,
+    { userWithSiteSessionData: UserWithSiteSessionData }
+  > = async (req, res) => {
+    // Step 1: Check that the site exists
+    const { siteName, requestId: prNumber } = req.params
+    const site = await this.sitesService.getBySiteName(siteName)
+
+    if (!site) {
+      return res.status(404).send({
+        message: "Please ensure that the site exists!",
+      })
+    }
+
+    // Step 2: Check that user exists.
+    // Having session data is proof that this user exists
+    // as otherwise, they would be rejected by our middleware
+    const { userWithSiteSessionData } = res.locals
+
+    // Check if they are a collaborator
+    const role = await this.collaboratorsService.getRole(
+      siteName,
+      userWithSiteSessionData.isomerUserId
+    )
+
+    if (!role) {
+      return res.status(400).send({
+        message: "User is not a collaborator of this site!",
+      })
+    }
+
+    // Step 3: Retrieve review request
+    const possibleReviewRequest = await this.reviewRequestService.getReviewRequest(
+      site,
+      prNumber
+    )
+
+    if (isIsomerError(possibleReviewRequest)) {
+      logger.error({
+        message: "Invalid review request requested",
+        method: "markReviewRequestAsViewed",
+        meta: {
+          userId: userWithSiteSessionData.isomerUserId,
+          email: userWithSiteSessionData.email,
+          siteName,
+          prNumber,
+        },
+      })
+      return res.status(404).json({ message: possibleReviewRequest.message })
+    }
+
+    // Step 4: Mark review request as viewed
+    await this.reviewRequestService.markReviewRequestAsViewed(
+      userWithSiteSessionData,
+      site,
+      possibleReviewRequest.id
+    )
+
+    return res.status(200).json()
+  }
+
   getReviewRequest: RequestHandler<
     { siteName: string; requestId: number },
     { reviewRequest: ReviewRequestDto } | ResponseErrorBody,
@@ -786,6 +850,10 @@ export class ReviewsRouter {
       "/:requestId",
       attachReadRouteHandlerWrapper(this.getReviewRequest)
     )
+    router.post(
+      "/:requestId/viewed",
+      attachWriteRouteHandlerWrapper(this.markReviewRequestAsViewed)
+    )
     router.post(
       "/:requestId/merge",
       attachWriteRouteHandlerWrapper(this.mergeReviewRequest)
diff --git a/src/services/review/ReviewRequestService.ts b/src/services/review/ReviewRequestService.ts
index e4fa863c7..78a767e07 100644
--- a/src/services/review/ReviewRequestService.ts
+++ b/src/services/review/ReviewRequestService.ts
@@ -285,18 +285,41 @@ export default class ReviewRequestService {
     const { isomerUserId: userId } = sessionData
     const { id: reviewRequestId } = reviewRequest
 
-    await this.reviewRequestView.update(
-      {
-        lastViewedAt: new Date(),
+    await this.reviewRequestView.upsert({
+      reviewRequestId,
+      siteId: site.id,
+      userId,
+      lastViewedAt: new Date(),
+    })
+  }
+
+  markReviewRequestAsViewed = async (
+    sessionData: UserWithSiteSessionData,
+    site: Site,
+    requestId: number
+  ): Promise<void> => {
+    const { isomerUserId: userId } = sessionData
+
+    const reviewRequestView = await this.reviewRequestView.findOne({
+      where: {
+        siteId: site.id,
+        userId,
+        reviewRequestId: requestId,
       },
-      {
-        where: {
-          reviewRequestId,
-          siteId: site.id,
-          userId,
-        },
-      }
-    )
+    })
+
+    // We only want to create the entry if it does not exist
+    // (i.e. the review request has never been viewed before)
+    if (!reviewRequestView) {
+      await this.reviewRequestView.create({
+        reviewRequestId: requestId,
+        siteId: site.id,
+        userId,
+        // This field represents the user opening the review request
+        // itself, which the user has not done so yet at this stage.
+        lastViewedAt: null,
+      })
+    }
   }
 
   deleteAllReviewRequestViews = async (