"The Soyuz-2.1b launch vehicle together with the Fregat booster and 34 @OneWeb communication satellites lifted off from the #Baikonur cosmodrome", Roscosmos said on Twitter.
The launch was initially planned for August 20th, but was postponed twice - the second time at the request of OneWeb itself.
The next launch of OneWeb satellites from Baikonur is planned for September.