Booker is unable to play in the game or participate in the 3-point contest because of a left knee sprain.
Conley, 33, becomes a first-time All-Star in his 14th season. He's the first player in NBA history to make his All-Star debut that far into his career.
The veteran point guard is averaging 16.1 points and 5.7 assists while shooting a career-high 42.2% from 3-point range. Conley will replace Booker in the 3-point contest as well.
NBA commissioner Adam Silver made the decision to replace Booker with Conley, giving the league-leading Jazz three representatives in the All-Star Game.
His addition to the All-Star roster is a feel-good story for Conley, who has routinely been in the All-Star discussion for a decade without ever making the team.
Lol What just happened— Mike Conley (@MCONLEY10) March 6, 2021
Booker sprained his knee in the first quarter of a victory over Golden State on Thursday. He appeared to bump knees with Kent Bazemore and fell to the floor with a grimace on his face. He remained in the game and finished with 16 points.
Booker was set to play in his second All-Star Game after he was put on the roster as an injury replacement for Los Angeles Lakers forward Anthony Davis, who is out with a calf strain and Achilles tendinosis.
The Associated Press contributed to this report.