SMU (12-4, 2-2 American Athletic Conference) never trailed, scoring the first 13 points and owned a double-digit lead from four minutes after tipoff for the rest of the game. Their largest lead was 26 late with 4:16 remaining.
Kennedy, a 6-foot-9 sophomore transfer who played previously for Villanova, made his second consecutive start since SMU's starting center, 6-11 junior Yanick Moreira, injured his right knee in practice last Thursday.
Kennedy is SMU's second-leading scorer this season despite coming off the bench for the first 14 games. He made his first start last Saturday in a 71-63 loss at then-No. 12 Louisville. Moreira will be out for three to six weeks.
SMU went into the game ranked fourth in Division I in field-goal defense, allowing 36.5-percent shooting, and held South Florida to 32.1 percent.
SMU raced to the 13-0 lead in the first 4:39 while South Florida missed its first six field-goal attempts and committed three turnovers.
The Mustangs were so hot they missed a free-throw attempt before missing from the field -- and got the offensive rebound on the missed free throw to convert it into a basket.
When USF freshman guard Josh Heath sailed an intended alley-oop pass out of bounds, SMU came down court and responded with a successful alley-oop from Williams to Kennedy.
The SMU first-half lead reached 19 points with 7:04 left before intermission at 30-11.
USF played its seventh consecutive game without junior point guard Anthony Collins, a three-year starter sidelined with knee problems.
Zach LeDay led South Florida (10-7, 1-3), with 12 points off the bench.