The Ireland international has been a vital part of the Galaxy since his arrival in 2011, and scored 16 goals and 11 assists in 23 MLS appearances last season.
Keane has been a revelation since joining the Galaxy from Tottenham in August 2011, scoring 34 goals and adding 21 assists in 55 MLS appearances. He has been named to the MLS Best XI for the past two seasons.
The 33-year-old also helped his team win back-to-back MLS Cups in 2011 and 2012 before LA's bid for a third consecutive title was derailed by Real Salt Lake last season.
Internationally, Keane has represented Ireland since 1998. The Dublin native has scored 62 goals in 131 appearances for his country.