The L.A. Rams running back threw on his best Santa coat and red beanie for a big Christmas event at a mansion in the Hollywood Hills on Monday night.

Gurley seemed to be moving around the party pretty well -- sipping on drinks, posing for pics and even dancing around a little bit.

It's not like he was running wind sprints in the backyard -- but it was a big mansion with stairs and he handled it all just fine.

Gurley aggravated the injury in his left knee during Sunday night's game against the Philadelphia Eagles -- and coach Sean McVay has said he'll be monitoring the knee going into Week 16.

"If he's able to go, we want him to be able to go," McVay told the media ... "But, if it's something that whether you're playing for the playoffs or whether you're not, we're always going to be smart with a player like Todd."

Gurley wasn't the only star at the party -- comedian Michael Blackson was there with an attractive female friend.