To make room on their roster, the Sabres sent another rookie defenseman, Rasmus Ristolainen, to their American Hockey League affiliate in Rochester.
Zadorov was taken with the 16th pick of the 2013 NHL Draft, eight spots after the Sabres chose Ristolainen. The Russian missed Buffalo's first nine games of the season while recovering from a finger injury he sustained blocking a shot during the preseason.
Ristolainen had no points and a minus-4 rating in eight games, averaging 16:52 of ice time per game.
Zadorov will be the eighth player taken in the first round of the 2013 draft to play a game this season.