The deal, agreed to ahead of the 6 p.m. ET deadline for rookie scale extensions, allows Hunter to avoid restricted free agency next summer.
Hunter, 24, averaged 13.4 points in 53 games last season for Atlanta, along with shooting a career-best 37.9% from 3-point range. Hunter's skillset fits ideally with Atlanta's blueprint for the future and he joins All-Star Trae Young and forward John Collins on long-term deals as franchise cornerstones.
The combination of Hunter and newly acquired Dejounte Murray on the wings give coach Nate McMillan the kind of defense and athleticism to pair with Young on the perimeter that the Hawks hope will boost their 26th-rated defense from a year ago.
Hunter, the 4th overall pick in the 2019 NBA draft, becomes the 11th player from that draft class to sign an extension this offseason, joining Zion Williamson, Ja Morant, RJ Barrett, Darius Garland, Tyler Herro, Brandon Clarke, Nassir Little, Jordan Poole, Keldon Johnson and Kevin Porter Jr.
Extending Hunter means the Hawks have four members of their starting five -- Young, Hunter, Collins and Clint Capela -- signed for at least the next three seasons, and Murray signed for the next two.
The Hawks traded up to acquire Hunter in the draft, making a deal with the Pelicans to move up from the eighth pick to the fourth selection to grab the former University of Virginia star.
Hunter had a tremendous first-round Eastern Conference playoff series against the Miami Heat, averaging 21.2 points on 56% shooting from the field and 46% on 3-pointers. He scored 35 points in Game 5, becoming only the third Hawks player with 35 points and 10 rebounds in a playoff game in the past 50 years, according to ESPN Stats and Information research.
Hunter was the primary defender on Miami's Jimmy Butler too, defending 24 of his shot attempts, per ESPN tracking.
During the regular season, Hunter matched up on defense 761 times against 2022 NBA All-Stars, according to ESPN Stats and Information research. The 2022 All-stars recorded a 45.7% effective field goals percentage when facing Hunter -- that ranked him top-10 among 57 players to record 500-plus matchups.
Phoenix's Cam Johnson, Washington's Rui Hachimura, Charlotte's PJ Washington and Boston's Grant Williams were among those who failed to reach an extension before the deadline and are set to hit restricted free agency next offseason.
ESPN NBA reporter Tim Bontemps contributed to this report.