No penalty was assessed on the play in the first period of the Panthers' 4-1 road loss.
The suspension will cost Winchester $9,231.
Early in the first period Thursday, Winchester left his feet and caught Kelly in the head with the blow. Kelly remained on the ice for a moment and was tended to by team trainer Donnie DelNegro before skating off the ice and going to the locker room. Kelly seemed dazed but quickly returned to action.
"I looked at the hit, the league looked at it. I wasn't going to say anything about it. Those kinds of things you let the league take care of it," Bruins coach Claude Julien said following the team's practice Friday morning, before Winchester's punishment was announced. "I'm just happy Chris was able to come back, and he did. As Chris said, the player that hit him is a former colleague of his, and [Winchester] is a nice guy, I know him as well. I don't think there was a real intent to injure more than it was a reckless hit, and that's why the league is looking into it."
Kelly and Winchester were former teammates in Ottawa, and the Bruins assistant captain showed no ill will toward him.
"I haven't seen the replay," Kelly said. "I did see that he's getting a hearing. The league will make the proper decisions. I don't want to comment on it either way. I'll let them handle it."
ESPNBoston.com's Joe McDonald and The Associated Press contributed to this report.