Siakam returned after missing 10 games because of a strained right adductor. The All-Star forward was injured when he slipped and fell in the third quarter of a Nov. 4 loss at the Dallas Mavericks. Toronto went 5-5 in his absence.
"He was really good,'' Raptors coach Nick Nurse said. "Looked really like he hadn't missed a beat.''
Siakam shot 7 for 14 and made one of three from 3-point range.
"Watching Pascal play is just like, 'Wow,''' Barnes said. "Every move he makes, the step-backs, the spin moves, double spin moves. It's great to have him back out there on the floor.''
Barnes returned after missing two games because of a sprained left knee. Last season's NBA Rookie of the Year came off the bench for the first time in a regular-season game.
'They have to come see us twice at home, too,'' Garland said. "Hopefully we get them back twice.''
Cleveland won eight straight following a season-opening loss at Toronto, and it returned to Canada having won five of its past six.
But the Cavaliers shot 7 for 38 from 3-point range, their fewest made 3s of the season and their lowest percentage at .184.
"Shots just didn't fall for us tonight,'' coach J.B. Bickerstaff said.
Cleveland matched its previous season low with eight 3-pointers in Sunday's win at Detroit. Cleveland was 3 for 11 from long distance in the first quarter, 3 for 10 in the second and 0 for 8 in the third. Caris LeVert connected with 2:17 to play in the fourth, giving the Cavs their only 3-pointer in 17 second-half attempts.
Siakam made Toronto's first two baskets and scored eight points in a seven-minute stint in the first quarter. The Raptors led 26-24 after one.
"He made tough shots in that first half,'' Bickerstaff said. "That gave them energy, gave them a boost.''
Siakam scored nine points in the second and VanVleet added seven as the Raptors made four of six from 3-point range to lead 52-43 at halftime. Toronto took an 80-67 lead into the fourth.
The Associated Press contributed to this story.