Irving scored 12 of his 35 points in the fourth quarter, and the Celtics won their ninth in a row after two opening losses, defeating the Hawks 110-107.
"He made huge plays down the stretch," coach Brad Stevens said of Irving. "I thought he not only made the plays, but he made a lot of right reads, too."
Irving, acquired by Boston from the Cleveland Cavaliers before the season, made four 3-pointers, shot 14 of 22 overall and dished out seven assists in his best game with the Celtics. He was coming off an 11-point outing in a Sunday victory at Orlando.
"When you're coaching against people, I always look at the box score for the game before," Stevens said. "If they really struggled but they're really good, that's just scary stuff. Guys like that don't have quiet nights twice in a row."
Irving, who also had seven assists against the Hawks, is averaging 22.3 points, 5.7 assists and an NBA-best 2.2 steals per game.
"It's exciting to be out there on his side, watching him do all those incredible things," said Celtics rookie Jayson Tatum, who had an impressive game himself. "He's a great player."
Tatum scored 21 points, including a big late 3-pointer, and grabbed eight rebounds. Former Atlanta forward Al Horford had 15 points, 10 rebounds and nine assists.
The Celtics (9-2) won despite 13-of-26 3-point shooting by the Hawks. Boston hadn't allowed more than 94 points in any of the previous games during the winning streak.
The Celtics led by 10 points early in the fourth quarter, but the Hawks battled back to take a 96-95 lead with about five minutes left on back-to-back 3-point baskets by Malcolm Delaney and Kent Bazemore.
After Delaney's third 3-pointer of the quarter put the Hawks up 103-101 with just under two minutes left, Irving matched the 3-pointer and Tatum hit one with 47 seconds remaining, putting the Celtics back in control.
"I'd made two from the same spot before, so I had the confidence to knock it down," Tatum said. "It felt great to contribute to a big win like this."
Stevens called a quick timeout in the third quarter to get the team's attention, and Irving, hitting two 3-pointers, scored eight points in a 13-0 run that overcame a seven-point Atlanta advantage en route to an 82-75 lead going into the fourth.
"We had to get our act together," Irving said. "You could just tell that mentally and physically, we were dragging a little bit."
Irving scored 11 of his 16 first-half points in the second quarter, but it was 54-54 at intermission thanks to 55 percent shooting by the Hawks.
"He's a top point guard in the league," Schroder said of Irving. "It's always great to play against the best players in the NBA. I learned tonight."
Schroder and Dedmon each had 13 points at the break for Atlanta, combing to make 11 of 15 shots. The Hawks shot 65 percent in the second quarter, when Schroder had all except two of his first-half points.
Both teams made 39 of 81 shots overall (48.1 percent).
The Hawks snapped an eight-game losing streak that followed an opening win at Dallas with a victory in Cleveland on Sunday.
"It would have been sweet to win two in a row against those kinds of teams, but we came up short," Schroder said.
"We can execute better down the stretch," Hawks coach Mike Budenholzer said. "The most important thing is how we competed. I think we got better tonight."
NOTES: F/C Aaron Baynes started for the Celtics with F Marcus Morris not yet cleared for back-to-back games, but Baynes had just two points in 14 minutes. ... Morris, coming back from knee surgery, averaged 10.5 points and 5.5 rebounds in his first two games. ... Hawks G Malcolm Delaney returned after missing two games with a sprained ankle. He scored 13 points. ... The Hawks are still without F Ersan Ilyasova (ankle), F Mike Muscala (ankle), C Miles Plumlee (quad) and F DeAndre Bembry (wrist). ... The Celtics play their next three games at home, starting against the Los Angeles Lakers on Wednesday. ... After playing three games in four days like the Celtics, the Hawks are off until starting a three-game trip at Detroit on Friday.