Malkin, 24, suffered a torn ACL and MCL during Friday's game against Buffalo when he collided with Buffalo Sabres defenseman Tyler Myers while racing for a loose puck in the corner.
Malkin was helped off the ice after the mishap. An MRI exam performed Saturday revealed the tears, Bylsma said, adding that the typical recovery time for such injuries is 4-to-6 months.
Malkin had just returned to the ice after missing five games and the All-Star Game due to a sinus infection and knee problem. He had 15 goals and 37 points in 43 games this season.