The Ireland skipper won and duly converted a penalty as Galaxy triumphed 4-2 on aggregate against Seattle Sounders to progress to their second successive MLS Cup
However, despite the defeat, Galaxy triumphed in the tie on aggregate by a score of 4-2 and Keane's penalty took the momentum out of Sounders as they sought to overturn the deficit.
LA Galaxy were trailing by two goals before Keane won a penalty on 67 minutes when Swedish defender Adam Johansson was adjudged to have handled the ball.
The Boys in Green record goalscorer stepped up and confidently converted the spot kick and the tie finished 4-2 on aggregate.
LA Galaxy will now face Houston Dynamo in the MLS Cup, on December 1.