Chicago Bears QB Jimmy Clausen tied the knot this weekend ... marrying pro volleyball star Jess Gysin ... and a bunch of NFL superstars were there to watch the whole thing go down.

Jimmy and Gysin had been dating since 2012 ... despite the fact they attended rival colleges -- he went to Notre Dame, she played ball at USC.

The two tied the knot in a ceremony in Palm Desert -- in front of some of Jimmy's old teammates ... including Golden Tate (who played with JC at ND) and Jonathan Stewart (who played with JC in Carolina).