Wendell Carter Jr. added 16 points and 10 rebounds for Duke (24-5, 12-4 Atlantic Coast Conference), which holds second place with two games remaining though it's out of contention for even a share of the regular-season title behind Virginia.
Duke had gone 4-0 without Bagley, with senior guard Grayson Allen the team's scoring leader in each of those games.
Bagley, the ACC's scoring and rebounding leader, returned for Duke after missing four games with a mild knee sprain. He came off the bench for the first time this season, checking in as the game's first substitute.
Tyus Battle's 12 points and Frank Howard's 11 points paced Syracuse (18-11, 7-9), which had three of its six 3-point baskets in the final three minutes.
The Orange were in desperate need of a quality victory following a four-point home loss Wednesday night to No. 10 North Carolina.
The teams combined for 24 consecutive missed 3-pointers before Oshae Brissett's long ball to pull the Orange within 29-21.
Duke didn't score for almost 4½ minutes to begin the second half, but Syracuse had only two points during that stretch.
Carter's dunk on a fast break pushed the lead to 41-30 with 8:37 left.
Syracuse center Paschal Chukwu fouled out with 6:45 remaining. He scored all six of his points in the first half, though he ended up with 12 rebounds.
Bagley had 14 points by halftime, helping the Blue Devils to a 27-16 advantage. There was little flow for either team.
Duke, the ACC's top-scoring team, shot 31 percent in the first half, but that was better than the 27.6 percent for the Orange, who also committed nine turnovers.
The teams combined to shoot 0-for-20 on first-half 3-point attempts, both sides going 0-for-10.
Duke was 9-for-10 on free throws, while Syracuse didn't have an attempt. The Orange were in the bonus in the second half with 9:49 remaining.
Duke broke out to an 18-8 lead, with Syracuse not cracking double figures until 13½ minutes had passed.
--Field Level Media
Syracuse | Duke | |
Tyus Battle 12 | Scoring | Marvin Bagley III 19 |
Frank Howard 7 | Assists | Grayson Allen 6 |
Paschal Chukwu 12 | Rebounds | Wendell Carter Jr. 10 |
Tyus Battle 2 | Free Throws Made | Wendell Carter Jr. 6 |
Tyus Battle 2 | Steals | Wendell Carter Jr. 4 |
Matthew Moyer 2 | Blocks | Wendell Carter Jr. 2 |