The 6-foot-3, 200-pound Russian, who was chosen in the first round (No. 12) of the 2012 NHL Draft, had one goal, five points and a minus-2 rating in 22 games for the Sabres.
The 18-year-old, who earned a bronze medal for Russia at the 2013 World Junior Championship in Ufa, Russia, in January, scored his first NHL goal on Jan. 29 in a 4-3 overtime loss to the Toronto Maple Leafs.
Grigorenko won 42 of 119 faceoffs this season for the Sabres. In 32 games for the Remparts during the NHL work stoppage, Grigorenko had 29 goals, 50 points and plus-9 rating.
"This is driven by what is best for Mikhail and his career," Sabres general manager Darcy Regier said in announcing the move.