The Crimson Tide (7-3, 2-0 Southeastern Conference) turned a one-point halftime lead into a double-digit advantage midway through the second behind Pettyās trio of 3s and two more long-range makes by Joshua Primo.
Primo and Herbert Jones finished with 11 points, and Jahvon Quinerly scored 10.
Tennessee (7-1, 1-1) struggled from the field the entire game, hitting 21 of 66 shots (32%).
Alabama's 31-29 lead at the break happened with the Crimson Tide shooting 39% (12 of 31), while Tennessee struggled shooting 33% (11 of 33).
UP NEXTAlabama: The Crimson Tide will be home Tuesday to face Florida, which beat LSU on Saturday.