The 37-year-old is in line to end his six-year Galaxy stay in style as they defend their title against the Houston Dynamo on December 1 before seeking to extend his playing career elsewhere.
He said: "I've had an incredibly special time playing for the LA Galaxy, however, I wanted to experience one last challenge before the end of my playing career."
Although Beckham had an option on his contract, signed in January, for another year with the Galaxy, his decision to leave is no great surprise.
Football Federation Australia last week claimed they had been approached by the former Real Madrid and Man-chester United star's camp with a view to the player spending a short stint in the A-League, though his spokesman described that as "rubbish".
Perth Glory – one of the clubs to express an interest when the links with Beckham going Down Under first emerged – were quick to go public again this morning, tweeting: "David Beckham has confirmed the MLS Cup final will be his last game for the Galaxy. The race is on."
China, the UAE, Paris, England and even Brazil have been mentioned as potential destinations but wherever he goes, it will bring to an end an eventful career in MLS which saw him become the face of a new era for the sport in North America.
His final game will take place at the Galaxy's own Home Depot Center, where he arrived on the American stage as the first designated player in MLS back in 2007.
"I don't see this as the end of my relationship with the league as my ambition is to be part of the ownership structure in the future," Beckham added.
Beckham's stint in Los Angeles brought success in the form of the Galaxy's third MLS Cup crown last year.
Beckham was brought to America as much for the effect of his brand as his on-field ability, and MLS commissioner Don Garber believes he has been successful in helping to grow the sport.
"When David Beckham signed with the LA Galaxy in 2007, he set out to help grow MLS and the sport of soccer in North America," he said.
"There is no doubt that MLS is far more popular and important here and abroad than it was when he arrived.
"David has achieved great things on and off the field during his time with the Galaxy, and he will always be an important part of our history. We look forward to his continued involvement with the LA Galaxy and the league."