The lead was 17 with about 5 minutes left when Marion stripped a driving Dragic, and Darren Collison flipped the ball to Jones for an easy dunk and a 102-83 lead for the Mavericks, who are still on the outside of the playoff picture heading into a four-game road trip that ends in Oklahoma City.
"Honestly, this was as close to a must win as we have in the regular season," Nowitzki said.
Elton Brand played his 900th career game and finished with 12 points for Dallas.
The Mavericks, who had their eighth straight game with at least five double-figure scorers, had four different players score during an 11-0 run bridging the first and second quarters. Nowitzki hit a jumper, Carter and Rodrigue Beaubois had consecutive 3-pointers and Jones converted a three-point play for a 38-21 lead.
Dallas pushed the lead out to 46-26 on a layup from Chris Kaman and back-to-back buckets by Marion, who had six straight points in the second and finished the half with a game-high 12.
Collison, whose streak of 16 straight double-figure games ended, was scoreless on just one shot attempt in the first half but led Dallas with four assists before halftime.
The Suns settled for a lot of long jumpers and shot 38 percent in the first half, going 1 for 9 from 3-point range.
Luis Scola finished with 14 points for Phoenix, while Michael Beasley and P.J. Tucker had 12 apiece.
"When you put yourself in a hole like that and you finally dig yourself out, to sustain it takes a lot out of you," said Hunter, who fell to 2-2 since replacing Alvin Gentry. "We just couldn't sustain it."
NOTES: Most of the game was played with a two-man officiating crew after Leroy Richardson strained his right calf early in the first quarter and didn't return. ... The Mavericks decided to keep veteran G Mike James at the end of his second 10-day contract, which guarantees his contract for the rest of the season. He played just 1:28 of the fourth with the outcome settled. ... Eight of the Suns' first nine games under Hunter will be part of a back-to-back set. ... James' start made it the 17th different starting lineup for Dallas this season.