Earlier this year, Tatum, 22, also earned his first All-Star nod.
The forward is one of only two Celtics to earn all-league honors before turning 23, according to the team. The other is Ed Macauley, who did it way back in 1951.
The NBA’s first team is anchored by LeBron James, who now stands alone in All-NBA recognition history.
James was named an All-NBA player for a record 16th time, breaking the tie he shared with Kareem Abdul-Jabbar, Kobe Bryant, and Tim Duncan. He was a first-team pick on all 100 ballots, joining Milwaukee’s Giannis Antetokounmpo as the only unanimous first-team selections this season.
Joining them on the first team: Houston guard James Harden, Lakers forward Anthony Davis, and Dallas guard Luka Doncic, who got the nod in just his second season — the first player to do that since Duncan in 1998-99.
The 21-year-old Doncic is the sixth player to make All-NBA at that age or younger, joining Kevin Durant, James, Duncan, Rick Barry, and Max Zaslofsky.
James is a first-team pick for the 13th time in his career, extending his record there. Bryant and Karl Malone were 11-time first-teamers. Antetokounmpo, the reigning MVP and the front-runner to win the award again this season, was picked unanimously for the second consecutive year.
Clippers forward Kawhi Leonard, Denver center Nikola Jokic, Portland guard Damian Lillard, Oklahoma City guard Chris Paul, and Toronto forward Pascal Siakam were on the second team.
Joining Tatum on the third team were Miami forward Jimmy Butler, Utah center Rudy Gobert, Philadelphia guard Ben Simmons, and Houston guard Russell Westbrook.
Paul and Westbrook are now nine-time All-NBA players, Harden a six-time choice, Lillard is a five-timer, and Antetokounmpo, Leonard, and Davis are four-time selections. Butler and Gobert are three-time selections, Jokic a two-time choice, and Siakam, Tatum, and Simmons all joined Doncic as being on the team for the first time.
Harden and Doncic appeared on all 100 ballots — though only James and Antetokounmpo were unanimous as first-team choices. on every ballot. Davis and Jokic were on 99 ballots, and Leonard appeared on 98.