The Raptors blew a 23-point lead but outlasted the stubborn Wizards, who never led until early in the second extra period, The Associated Press reported.
Toronto, which was led by Kawhi Leonard's 41 points and 11 rebounds, led 51-28 with four minutes to play in the second quarter and 96-79 with 57 seconds to play in the third.
Bradley Beal had his second triple-double of the season, collecting season highs of 43 points and 15 assists along with 10 rebounds. His three-pointer with 20.4 seconds left in regulation tied it at 124 to force overtime. His jumper with 6.8 seconds to play in the first overtime tied it at 131.
Leonard had 13 straight points in the fourth quarter and overtime. Toronto missed 7-of-9 from the field in the second OT and didn't score for nearly 3.5 minutes, but Washington could only push ahead by three points during that stretch.
Pascal Siakim scored 24 and had a career-high 19 rebounds for the Raptors.
Otto Porter, who had 27 points, missed a three-pointer with six seconds to play in the second OT.
Trevor Ariza narrowly missed his second career triple-double. He had 23 points, 10 assists and nine rebounds before fouling out with 44.7 seconds left.