Durant's monster game, which included a 21-of-21 performance from the foul line, halted a four-game Dallas winning streak.
O.J. Mayo hit a 3-pointer for the Mavericks with 2.3 seconds left in the fourth quarter to force the extra period and Dallas then jumped in front by three early in overtime.
Vince Carter failed at the buzzer on a 3-point attempt that would have brought about a second overtime.
Durant's 52 points were easily the most he has scored in a game this season and Westbrook added 31. They combined to produce more than 70 percent of Oklahoma City's offense.
Carter had 29 points to lead Dallas while Mayo and Dirk Nowitzki both had 18.