Financial details of the plan were not released but NBA Commissioner David Stern said the settlement called for training camps and the league's free agency period to begin on December 9.
"We've reached a tentative understanding that is subject to a variety of approvals and very complex machinations," Stern told a news conference early on Saturday after a 15-hour negotiating session.
"But we're optimistic that will all come to pass and that the NBA season will begin on December 25, Christmas Day, with a triple-header.
"We're very pleased that we've come this far. There's still a lot of work to be done in a lot of places, with a lot of committees and player groups and the like.
"But we're optimistic that it will hold and we'll have ourselves an NBA season."