Graham also had eight rebounds for the Raptors, who never trailed.
"He played well tonight. That's all I know," Mitchell said. "If I knew what he had for lunch or what he did at home, I'd videotape it and show it to him before every game. We need Joey to play like that."
Graham went 8-for-14 from the field and surpassed his previous high of 17 points set Dec. 29 against Chicago. The second-year swingman came off the bench against Atlanta, but has started of late as Mitchell searches for his best option at small forward.
"When you hit your first couple of shots it gives you confidence," Graham said. "I came into the game and scored four quick points. The sky is the limit after that."
Andrea Bargnani, the No. 1 pick in the draft, had 12 points in his first start at small forward for Toronto. Bargnani made a nice reverse bounce pass to Bosh in the second half, but Bosh couldn't convert the dunk.
Mitchell said the 7-footer started at small forward so he could match up with 6-foot-9 Marvin Williams, who had 24 points for the Hawks.
Backup point guard Jose Calderon added a season-high 12 assists and 12 points for the Raptors, who had five players score in double figures. Starting point guard T.J. Ford missed his third straight with a sprained right ankle.
Toronto shot 55 percent, compared to 48 percent for Atlanta. Bosh went 8-for-11 from field in his second game since missing 12 straight with an injured left knee.
Bosh played just 33 minutes with Toronto leading throughout.
"It was a little nice to get some rest," Bosh said.
Mitchell said they'll continue to rest and treat Bosh to make sure he's healthy.
Atlanta won its previous two games against Toronto, but was missing Josh Smith (hernia surgery). Toronto outscored Atlanta 44-28 in the paint.
"We have a lot of guys injured, but that's not to make an excuse," point guard Speedy Claxton said. "We just got to get some guys healthy and start believing we can win again, and start playing defense."
Graham had 13 points and Bosh added 12 as Toronto led 58-46 at halftime. Toronto shot 66 percent in the half.
Morris Peterson's consecutive 3-pointers gave Toronto an 89-73 lead with 7:13 left in the fourth quarter.
Claxton converted a four-point play to cut the lead to 10 with 3:17 left, but Peterson made a running jumper and Bosh made two free throws 3:02 left.
- Graham's twin brother, Stephen, watched from the stands. Portland waived Stephen on Tuesday.
- The Raptors assigned rookie forward P.J. Tucker to the Colorado 14ers of the NBA Development League on Friday. Tucker averaged 1.5 points and 1.3 rebounds in 16 games. He was drafted in the second round out of the University of Texas.
- Former NFL and CFL quarterback Doug Flutie sat courtside.