Jason L. Lambert (born September 23, 1977) is a mixed martial artist from Victorville, California, who fought in the light heavyweight division for the Ultimate Fighting Championship prior to being released from the company. He fights out of North County Fight Club and is represented by NCFC Fight Management.

Lambert made his debut in the UFC at UFC 58: USA vs. Canada as a late replacement for The Ultimate Fighter 2 cast member Seth Petruzelli, who suffered a concussion while training and had to withdraw from the bout. Lambert's debut was successful, submitting his opponent, Rob MacDonald, early in the first round.

Lambert fought again at UFC 59, defeating Terry Martin by technical knockout at 2:37 of round two. This was a preliminary fight that did not air on the pay-per-view broadcast. His next fight, against Branden Lee Hinkle at Ultimate Fight Night 5, marked Lambert's third consecutive UFC victory. Despite this initial win streak, he was not seen on a live UFC pay-per-view broadcast until UFC 63, where he lost to Rashad Evans by knockout in the second round. At UFC 68, Lambert defeated veteran and former title challenger Renato "Babalu" Sobral in a stunning upset by second-round knockout.

Lambert was scheduled to fight Wilson Gouveia at UFC 76: Knockout, but the bout was resqueduled to UFC 80: Rapid Fire after Gouveia suffered an injury in training. Lambert was knocked out by Gouveia by a left hook which, ironically, was identitical to the hook used by Lambert in his prior fight to finish Renato Sobral.

The 'Punisher' then lost at UFC 85: Bedlam via TKO at the hands of Luiz Arthur Cane at 2:07 of the second round. Lambert moved down to the middleweight (185 pounds) division for his most recent fight against Jason Macdonald at UFC 88: Breakthrough in Atlanta, Georgia, on September 6th, 2008, which he lost by rear naked choke at 1.20 in the second round.