Donovan, 32, will leave the game as the all-time scoring leader in MLS regular season play, entering Friday's clash with the San Jose Earthquakes with 138 goals in 320 career games.
"After careful deliberation and many conversations with those closest to me, I have decided that this will be my last year as a professional soccer player," Donovan said in a statement. "It has been more than anything I could have dreamed of to represent the L.A. Galaxy, the San Jose Earthquakes, Everton, U.S. Soccer and Major League Soccer throughout my career. There are so many people I want to thank who have inspired me, guided me and helped me on this incredible journey. I simply could not have accomplished what I did during my playing career without an overwhelming amount of support from my family, my friends and many others. I plan to express my gratitude to everyone in a more detailed manner at a later date; however, for now, I want to single out the fans. You are the lifeblood of this sport and, without you, none of us would be fortunate to call ourselves professional soccer players in MLS."
Donovan is one of American soccer's most-decorated players. The Ontario, Calif., native is a winner of five MLS Cups (2001, 2003, 2005, 2011, 2012), a Lamar Hunt U.S. Open Cup (2005) and two MLS Supporters' Shields (2010, 2011).
Individually, Donovan has been named to an MLS record 14 consecutive All-Star games (2001-2014), the MLS Best XI six times (2003, 2008, 2009, 2010, 2011, 2012), the MLS MVP and won the Golden Boot (2008) as well as being the only two-time MLS Cup MVP winner (2003, 2011).
"Landon Donovan is one of the most significant figures in the history of soccer in the United States," said Galaxy head coach Bruce Arena. "His influence on MLS and soccer in this country will continue to be felt for many years to come. As both a player and a person, Landon has been an incredible representative of the L.A. Galaxy, MLS and the U.S. men's national team and it has been my honor coaching him. We respect his decision to retire at the end of the season and look forward to competing for another MLS Cup and celebrating his outstanding career."
Donovan leads the U.S. men's national team in goals (57) and assists (58) and is the only American player to surpass both 50 goals and assists in his career. His 156 appearances are second-most all time in U.S. history.
A veteran of three World Cups, Donovan's five goals in World Cup matches are the most by any American player. He claimed FIFA's Best Young Player of the World Cup award in 2002 as well as CONCACAF Gold Cup MVP honors in 2013 in addition to being named to the Gold Cup Best XI four times (2002, 2003, 2005, 2013).