The specifics of the deal have not been disclosed but Galaxy coach Bruce Arena has spoken of his delight of the news.
Arena said: “We’re very pleased Robbie will continue to be a member of the Galaxy in the coming years.
“He has been one of the key pieces in our success over the past five seasons. We look forward to even more success with Robbie as a member of our team.”
Meanwhile, Aston Villa chief executive Tom Fox has confirmed Christian Benteke will be offered a new contract this summer to try to stave off interested clubs.
Benteke’s current contract has two years left to run and Villa manager Tim Sherwood has revealed the terms contain a buyout clause thought to be £32.5 million (€44.6m).
The striker signed that deal in July 2013 to end speculation linking him with a move to Tottenham and Villa now hope to pull off a similar manoeuvre this summer.
“There has been a lot of speculation and I’m not going to contribute to it or play any of our transfer strategy out in the press,” said Fox.
“But we will offer Christian Benteke a new deal this summer, of course we will.”
In other transfer news, West Ham have confirmed the signing of Spain U21 midfielder Pedro Obiang from Sampdoria for an undisclosed fee while Ghana forward Andre Ayew has joined Swansea on a four-year deal, subject to international clearance.