The Rams, who have already clinched a playoff berth, had gone into Monday's game in Atlanta hoping for a win to boost their postseason seeding.
But the 2022 Super Bowl champions found themselves chasing the game as already-eliminated Atlanta roared into a commanding halftime lead.
Robinson stood out for Atlanta in a dominant first-half display, rushing for a career-long 93-yard touchdown to give the Falcons a hefty 21-0 advantage at the break.
Robinson totaled 195 rushing yards and 34 receiving yards. He now becomes the first person since legendary wide receiver Jerry Rice to put up 200+ scrimmage yards in two Monday night games in a single season.
Robinson had already opened the scoring after gathering a short pass from Falcons quarterback Kirk Cousins in the first quarter to put Atlanta 7-0 up.
Jessie Bates then picked off Rams quarterback Matthew Stafford for a second quarter touchdown to help Atlanta take a 14-0 lead before Robinson's long-range effort left the Falcons in complete control.
Yet the Rams responded to a disastrous first two quarters to level the game in the second half.
Stafford found Terrance Ferguson with a 27-yard pass to help cut the Falcons' lead to 14 points before Jared Verse rumbled 76 yards for a touchdown after a blocked Gonzalez field goal attempt.
Stafford connected with receiver Puka Nacua to tie it at 24-24 with just under three minutes remaining in the fourth quarter, but Atlanta responded by moving Gonzalez into field goal range after the restart.
Gonzalez made no mistake with his game-winning effort, and the Falcons held on as Los Angeles fell to 11-5.