The Republic of Ireland skipper scored the third goal for Galaxy as they defeated Houston 3-1 at the Home Depot Centre
Houston took the lead through Calen Carr just before half-time but a header from Omar Gonzalez levelled the score in the second half. Landon Donovan then sent Galaxy into the lead when he scored from the spot on 65 minutes.
Former Liverpool and Tottenham Hotspur striker Keane then added to Galaxy's lead in the dying moments of the game. The 32-year-old striker won a penalty after being fouled by Hall and he duly dispatched the ball into the net to make 3-1 the final score.
Speaking to reporters after the game, Keane said that it was 'fantastic' to have won a second MLS Cup with LA Galaxy.
He said: "It’s obviously fantastic. It means a lot more this year than it did last year because I was here for the start of the season. It felt like I contributed a lot more this season than last season."
Despite going into the dressing room a goal down at half-time, Keane felt that Galaxy would win the game if they scored the first goal in the second half.
"We were fine," he told mlssoccer.com after the game. "Just kind of catching our breath, getting a little bit reorganized and understanding that the first 15 minutes of that second half, we had to keep ourselves in the game.
"I told [the team] at half time, ‘We get the first goal, we’ll win the game.’” added the Republic of Ireland international.