Garland was one of seven Cleveland players to finish in double figures as the Cavs' balanced offence overwhelmed Atlanta to claim their 39th victory of the season.
The blowout was especially sweet for Garland, who was named to next month's All-Star game along with team-mate Evan Mobley shortly before tip-off.
Atkinson expressed delight after Thursday's victory that so many of his starting line-up have been given All-Star recognition.
"So proud," Atkinson said. "You can't take that away from them. They'll have it on their resumes for the rest of their lives."
"To have three guys on the All-Star team - that's phenomenal ... It bodes well for our future because when you have talent and character like that in the locker room you can do special things."
While Garland led the Cleveland scoring, Mitchell also pitched in with 24 points while Mobley finished with 10 rebounds, four assists and 16 points. Ty Jerome (27) added 20 off the bench.
Frenchman Zaccharie Risacher (19) led Atlanta's scoring with 30 points, including five three-pointers, but Trae Young (26) had a frustrating outing, restricted to just 15 points.
Cleveland improved to 39-9 with the win and lead the Eastern Conference from second-placed Boston by six games. Atlanta fell to 22-26 with the defeat.
Lakers vs. Wizards
Elsewhere on Thursday, LeBron James (40) led from the front as the Los Angeles Lakers shrugged off the injury absence of Anthony Davis (31) to thrash the Washington Wizards 134-96 in the US capital.
James led the Lakers scoring with 24 points, 11 assists and three rebounds, including one audacious three-pointer from near the halfway line in a game that was over by half-time as Los Angeles poured in 78 points over the first two quarters.
Rui Hachimura (26) added 22 points, while Austin Reaves (26) finished with 17. Shake Milton (28) had an impressive 21 points from the bench while Bronny James (20) got among the points late in the fourth quarter as the clock wound down.
The Lakers improved to 27-19 with the win and are fifth in the Western Conference table. The Wizards are propping up the Eastern Conference with a league-worst 6-41 record and have now lost 16 straight games.
Lakers coach JJ Redick (40) paid tribute to the contribution of veteran star James in what was a bounce-back win after a chastening 118-104 defeat to struggling Philadelphia on Tuesday.
"He was awesome," Redick said of James. "He was aggressive. Just his willingness to trust his teammates, create for others and create for himself. It was awesome."
"Don't overlook the fact that he's 40 years old, in year 22 of his career, with every accolade under the sun. And he comes out on a Thursday night, in a non-nationally televised game against a team that is struggling and he's the tone-setter. Just his competitive stamina - it's impressive."
Around the league
(This section will be updated following the Memphis Grizzlies-Houston Rockets and Portland Trail Blazers-Orlando Magic games.)