Rodrigue Beaubois hit a 20-footer with 9.8 seconds left to give Dallas a 30-16 lead after the first quarter. Golden State, who missed 10 straight shots during one stretch, was 7 of 22 in the opening quarter.
The Mavericks pushed their advantage to 43-21 on Nowitzki's three-point play. Marion's dunk gave Dallas a 54-27 lead with 5:06 remaining in the first half.
"We started off aggressive on both ends of the floor and we were able to capitalize on their misses," Marion said. "We made them turn the ball over and that opened the game up."
Golden State, which trailed 62-36 at halftime, got within 87-74 early in the fourth.
Dallas answered with an 18-5 run, which was capped when Mayo saved a loose ball from going out of bounds near midcourt and hit a streaking Marion for a dunk that made it 105-79.
NOTES: Nowitzki passed Wilt Chamberlain for 15th place on the NBA's career list for free throws made. Nowitzki was 8 of 11 Saturday night and has 6,059 in his career. ... Golden State G Jarrett Jack (right shoulder) missed his third straight game. Warriors C Andrew Bogut also did not play. Bogut played a season-high 28 minutes Friday against Memphis on Friday, but the Warriors aren't playing the 7-footer on consecutive nights as he works his way back from left ankle surgery. ... After marching in the inaugural parade last month, the Grambling State band performed at halftime.