Pascal Siakam scored 21 points, Serge Ibaka had 14 points and 14 rebounds, and Kyle Lowry added 16 points and eight assists for the Raptors.
Toronto has won five straight since its lone loss this season at Milwaukee on Oct. 29.
Leonard returns from 2-game absence to lead Raptors:
Leonard sat out the previous two games and got off to a sluggish start early against the Kings before helping Toronto pull away.
The two-time All-Star scored 10 points in the second quarter and 10 in the third, including a soaring, one-handed dunk through traffic. Leonard also made a pivotal three-pointer in the fourth after Sacramento had pulled to 106-99.
Toronto has won three straight against the Kings.
Willie Cauley-Stein and Buddy Hield scored 24 points apiece for Sacramento. De’Aaron Fox added 20 points, and second overall draft pick Marvin Bagley III had 13.
The Kings have lost two straight since winning five in a row.
Toronto ended the first quarter on a 15-4 run, then took control once Leonard got going in the second after Sacramento got in foul trouble.
Leonard made five free throws in the period, one coming after frustrated Kings coach Dave Joerger was hit with a technical foul for arguing with officials. Leonard also had a three-pointer that put the Raptors up 49-40.
Danny Green added back-to-back threes and OG Anunoby followed with a steal and dunk as Toronto took a 64-51 halftime lead.