diff --git a/src/main.rs b/src/main.rs
index 7c1cc74..fb625b4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -36,6 +36,7 @@ pub fn get_api_scope<
 
     let users_scope = utoipa_actix_web::scope("/users")
         .wrap(JWTAuthorization)
+        .service(routes::users::change_username)
         .service(routes::users::me);
 
     let schedule_scope = utoipa_actix_web::scope("/schedule")
diff --git a/src/routes/users/change_username.rs b/src/routes/users/change_username.rs
new file mode 100644
index 0000000..1523c6f
--- /dev/null
+++ b/src/routes/users/change_username.rs
@@ -0,0 +1,75 @@
+use self::schema::*;
+use crate::app_state::AppState;
+use crate::database::driver;
+use crate::database::models::User;
+use crate::extractors::base::SyncExtractor;
+use crate::routes::schema::IntoResponseAsError;
+use crate::utility::mutex::MutexScope;
+use actix_web::{post, web};
+use diesel::SaveChangesDsl;
+
+#[utoipa::path(responses((status = OK)))]
+#[post("/change-username")]
+pub async fn change_username(
+    app_state: web::Data<AppState>,
+    user: SyncExtractor<User>,
+    data: web::Json<Request>,
+) -> ServiceResponse {
+    let mut user = user.into_inner();
+
+    if user.username == data.username {
+        return ErrorCode::SameUsername.into_response();
+    }
+
+    if driver::users::get_by_username(&app_state, &data.username).is_ok() {
+        return ErrorCode::AlreadyExists.into_response();
+    }
+
+    user.username = data.into_inner().username;
+
+    if let Some(e) = app_state
+        .database
+        .scope(|conn| user.save_changes::<User>(conn))
+        .err()
+    {
+        eprintln!("Failed to update user: {e}");
+        return ErrorCode::InternalServerError.into_response();
+    }
+
+    Ok(()).into()
+}
+
+mod schema {
+    use actix_macros::{IntoResponseErrorNamed, StatusCode};
+    use derive_more::Display;
+    use serde::{Deserialize, Serialize};
+    use utoipa::ToSchema;
+
+    pub type ServiceResponse = crate::routes::schema::Response<(), ErrorCode>;
+
+    #[derive(Serialize, Deserialize, ToSchema)]
+    #[schema(as = ChangeUsername::Request)]
+    pub struct Request {
+        /// Новое имя.
+        pub username: String,
+    }
+
+    #[derive(Clone, Serialize, ToSchema, StatusCode, Display, IntoResponseErrorNamed)]
+    #[serde(rename_all = "SCREAMING_SNAKE_CASE")]
+    #[schema(as = ChangeUsername::ErrorCode)]
+    #[status_code = "actix_web::http::StatusCode::CONFLICT"]
+    pub enum ErrorCode {
+        /// Передано то же имя, что есть на данный момент.
+        #[display("Passed the same name as it is at the moment.")]
+        SameUsername,
+
+        /// Пользователь с таким именем уже существует.
+        #[display("A user with this name already exists.")]
+        AlreadyExists,
+
+        /// Ошибка на стороне сервера.
+        #[display("Internal server error.")]
+        #[status_code = "actix_web::http::StatusCode::INTERNAL_SERVER_ERROR"]
+        InternalServerError,
+    }
+}
diff --git a/src/routes/users/mod.rs b/src/routes/users/mod.rs
index 0249b33..1b5d194 100644
--- a/src/routes/users/mod.rs
+++ b/src/routes/users/mod.rs
@@ -1,6 +1,7 @@
+mod change_username;
 mod me;
 
+pub use change_username::*;
 pub use me::*;
 
-// TODO: change-username
-// TODO: change-group
\ No newline at end of file
+// TODO: change-group