The launch took place at 20:07 Moscow time (17:07 GMT).
The Fregat booster with 34 satellites separated from the rocket minutes after the launch, according to the broadcast.
Roscosmos signed contracts with French company Arianespace and UK's OneWeb in June 2015 for carrying out a total of 21 commercial launches to bring 672 satellites to space atop the Soyuz rockets from Kourou, Baikonur and Vostochny spaceports.
OneWeb plans to create a constellation of satellites that will provide broadband internet access to users around the world fully covering the Earth’s surface.
On 16 March, the Soyuz-2.1b rocket with the Fregat and the satellite was launched at 21:28 Moscow time (06:28 pm GMT) from the Plesetsk space centre.