Mariinsky Posad (Russian: Марии́нский Поса́д; Chuvash: Сĕнтĕрвăрри, Sĕntĕrvărri) is a town and the administrative center of Mariinsko-Posadsky District in the Chuvash Republic, Russia, located on the right bank of the Volga River, 36 kilometers (22 mi) east of Cheboksary, the capital of the republic.

[3] It was first mentioned in 1620 as the selo of Sundyr (Сундырь), named after the Sundyrka River (a tributary of the Volga).

[2] It was granted town status and renamed Mariinsky Posad after Empress consort Maria Alexandrovna in 1856.

[1] As an administrative division, it is incorporated within Mariinsko-Posadsky District as Mariinsko-Posadskoye Urban Settlement.

[4] There are eleven processing, mechanical engineering, and construction materials factories in the town.