The current five-year deal is scheduled to expire at the end of January and there has been talk of a lockout or a players strike.
However, MLS Commissioner Don Garber said talks had yielded some progress.
"While we still have areas of disagreement, the talks have been constructive and both parties believe it makes sense to continue to work hard to reach agreement," said Garber in a joint statement with the union.
"This extension provides both MLS and the players the opportunity to continue our discussions while clubs are in training camps preparing for the 2010 MLS season."
MLS teams are currently reporting back for pre-season training camps ahead of the season, which is due to begin in March.
"Both the Players Union and MLS have concluded that a new agreement will not be reached by February 1, but we have agreed to continue to talk and we will be meeting over the next two weeks to determine if a new agreement can be reached," said MLS Players Union Executive Director Bob Foose.
"In the meantime, MLS Players are reporting to training camp, and preparations for the 2010 season will continue."
The new season will open with expansion franchise the Philadelphia Union away to the league's best supported team - the Seattle Sounders - on March 25.
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