OEVRZ submitted a bid of Roubles 10.5bn ($US 164m) for the contract, while its competitor in the tender, Škoda Transportation's Vagonmash subsidiary, offered a price of Roubles 10.51bn.
The order is being funded through the city of St Petersburg's 2015-2020 transport strategy, which was approved in June 2014, as well as the metro's own investment programme.
The trains will be assembled at OEVRZ's plant near St Petersburg and the contract stipulates that the first three sets must be delivered next year, followed by three in 2017, four in 2018, and five in 2020.
Earlier this year St Petersburg Metro awarded Vagonmash a Roubles 3.8bn contract to supply eight trains for Line 3.
