diff --git a/CHANGELOG.md b/CHANGELOG.md
index d516080b4..19cd1e539 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -50,6 +50,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Admin API: `/users/:nickname/toggle_activation` endpoint is now deprecated in favor of: `/users/activate`, `/users/deactivate`, both accept `nicknames` array
 - Admin API: `POST/DELETE /api/pleroma/admin/users/:nickname/permission_group/:permission_group` are deprecated in favor of: `POST/DELETE /api/pleroma/admin/users/permission_group/:permission_group` (both accept `nicknames` array), `DELETE /api/pleroma/admin/users` (`nickname` query param or `nickname` sent in JSON body) is deprecated in favor of: `DELETE /api/pleroma/admin/users` (`nicknames` query array param or `nicknames` sent in JSON body).
 - Admin API: Add `GET /api/pleroma/admin/relay` endpoint - lists all followed relays
+- Pleroma API: `POST /api/v1/pleroma/conversations/read` to mark all conversations as read
 
 ### Changed
 - **Breaking:** Elixir >=1.8 is now required (was >= 1.7)
diff --git a/docs/API/pleroma_api.md b/docs/API/pleroma_api.md
index 0517bbdd7..6c326dc9b 100644
--- a/docs/API/pleroma_api.md
+++ b/docs/API/pleroma_api.md
@@ -367,6 +367,13 @@ The status posting endpoint takes an additional parameter, `in_reply_to_conversa
     * `recipients`: A list of ids of users that should receive posts to this conversation. This will replace the current list of recipients, so submit the full list. The owner of owner of the conversation will always be part of the set of recipients, though.
 * Response: JSON, statuses (200 - healthy, 503 unhealthy)
 
+## `GET /api/v1/pleroma/conversations/read`
+### Marks all user's conversations as read.
+* Method `POST`
+* Authentication: required
+* Params: None
+* Response: JSON, returns a list of Mastodon Conversation entities that were marked as read (200 - healthy, 503 unhealthy).
+
 ## `GET /api/pleroma/emoji/packs`
 ### Lists the custom emoji packs on the server
 * Method `GET`
diff --git a/lib/pleroma/conversation/participation.ex b/lib/pleroma/conversation/participation.ex
index e17f49e58..41918fa78 100644
--- a/lib/pleroma/conversation/participation.ex
+++ b/lib/pleroma/conversation/participation.ex
@@ -69,6 +69,19 @@ def mark_as_read(participation) do
     end
   end
 
+  def mark_all_as_read(user) do
+    {_, participations} =
+      __MODULE__
+      |> where([p], p.user_id == ^user.id)
+      |> where([p], not p.read)
+      |> update([p], set: [read: true])
+      |> select([p], p)
+      |> Repo.update_all([])
+
+    User.set_unread_conversation_count(user)
+    {:ok, participations}
+  end
+
   def mark_as_unread(participation) do
     participation
     |> read_cng(%{read: false})
diff --git a/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex b/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
index 9d50a7ca9..fc39abf05 100644
--- a/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
+++ b/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
@@ -79,6 +79,15 @@ def update_conversation(
     end
   end
 
+  def read_conversations(%{assigns: %{user: user}} = conn, _params) do
+    with {:ok, participations} <- Participation.mark_all_as_read(user) do
+      conn
+      |> add_link_headers(participations)
+      |> put_view(ConversationView)
+      |> render("participations.json", participations: participations, for: user)
+    end
+  end
+
   def read_notification(%{assigns: %{user: user}} = conn, %{"id" => notification_id}) do
     with {:ok, notification} <- Notification.read_one(user, notification_id) do
       conn
diff --git a/lib/pleroma/web/router.ex b/lib/pleroma/web/router.ex
index d68fb87da..66e7a2263 100644
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@@ -266,6 +266,7 @@ defmodule Pleroma.Web.Router do
 
       get("/conversations/:id/statuses", PleromaAPIController, :conversation_statuses)
       get("/conversations/:id", PleromaAPIController, :conversation)
+      post("/conversations/read", PleromaAPIController, :read_conversations)
     end
 
     scope [] do
diff --git a/test/conversation/participation_test.exs b/test/conversation/participation_test.exs
index a5af0d1b2..64c350904 100644
--- a/test/conversation/participation_test.exs
+++ b/test/conversation/participation_test.exs
@@ -133,6 +133,20 @@ test "it marks a participation as unread" do
     refute participation.read
   end
 
+  test "it marks all the user's participations as read" do
+    user = insert(:user)
+    other_user = insert(:user)
+    participation1 = insert(:participation, %{read: false, user: user})
+    participation2 = insert(:participation, %{read: false, user: user})
+    participation3 = insert(:participation, %{read: false, user: other_user})
+
+    {:ok, [%{read: true}, %{read: true}]} = Participation.mark_all_as_read(user)
+
+    assert Participation.get(participation1.id).read == true
+    assert Participation.get(participation2.id).read == true
+    assert Participation.get(participation3.id).read == false
+  end
+
   test "gets all the participations for a user, ordered by updated at descending" do
     user = insert(:user)
     {:ok, activity_one} = CommonAPI.post(user, %{"status" => "x", "visibility" => "direct"})
diff --git a/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs b/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs
index 8a6528cbb..9cccc8c8a 100644
--- a/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs
+++ b/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs
@@ -95,6 +95,33 @@ test "PATCH /api/v1/pleroma/conversations/:id", %{conn: conn} do
     assert other_user in participation.recipients
   end
 
+  test "POST /api/v1/pleroma/conversations/read", %{conn: conn} do
+    user = insert(:user)
+    other_user = insert(:user)
+
+    {:ok, _activity} =
+      CommonAPI.post(user, %{"status" => "Hi @#{other_user.nickname}", "visibility" => "direct"})
+
+    {:ok, _activity} =
+      CommonAPI.post(user, %{"status" => "Hi @#{other_user.nickname}", "visibility" => "direct"})
+
+    [participation2, participation1] = Participation.for_user(other_user)
+    assert Participation.get(participation2.id).read == false
+    assert Participation.get(participation1.id).read == false
+    assert User.get_cached_by_id(other_user.id).info.unread_conversation_count == 2
+
+    [%{"unread" => false}, %{"unread" => false}] =
+      conn
+      |> assign(:user, other_user)
+      |> post("/api/v1/pleroma/conversations/read", %{})
+      |> json_response(200)
+
+    [participation2, participation1] = Participation.for_user(other_user)
+    assert Participation.get(participation2.id).read == true
+    assert Participation.get(participation1.id).read == true
+    assert User.get_cached_by_id(other_user.id).info.unread_conversation_count == 0
+  end
+
   describe "POST /api/v1/pleroma/notifications/read" do
     test "it marks a single notification as read", %{conn: conn} do
       user1 = insert(:user)