After Kamara had corralled a bobble while running between two converging defenders to score from 18 yards out, he took a pitch on a misdirection play to the left side and easily reached the end zone for a 2-point conversion as the Superdome crowd - at least those who hadn't left early - went wild.
Wil Lutz 28-yard field goal in overtime was the victor for the Saints.
The Saints are now 8-2 overall.
But in a methodical 3-minute drive, quarterback Drew Brees marched the Saints 75 yards in eight plays, capping the drive with a 3-yard scoring pass to tight end Josh Hill. And the defense crushed the ensuing Redskins drive to send the game to overtime.
His counterpart, Kirk Cousins threw for 322 yards and three touchdowns.
Aggressively looking down field against a hobbled Saints secondary, Cousins completed 22 of 32 passes with no interceptions.
The Redskins have suffered a number of injuries this season, but Thompson's could arguably be the biggest because of his productivity and the fact that he'll be hard to replace. Cousins is 10-of-14 for 139 yards and Perine has 57 yards on 11 carries as the Saints defense has looked more vulnerable than it has in several weeks. The kick was set up by two huge Mark Ingram runs, the first for 20 yards and the second for 31 yards.
With teammate Jordan Reed suffering a setback and being ruled out for Sunday's game versus the Saints the former Maryland standout will see a lot of action in the passing game and should be in Week 11 starting lineups.
After being outplayed for nearly the entire game, the Saints staged a comeback for the ages with a 34-31 overtime victory over the Washington Redskins on Sunday at the Mercedes-Benz Superdome.