Jonassen crunched an unbeaten 63 off 29 balls at Junction Oval to underpin the reigning champions' 5-153.
In reply, the Renegades fell short on 9-147, failing to repeat their final-ball heroics from Sunday's win over Sydney Sixers.
When Delissa Kimmince bowled Leah Tahuhu with the Renegades requiring a last-ball six to force a super over, the Heat were jubilant, banking their sixth successive win.
Opener Danni Wyatt made 40 off 18 balls to get the Renegades off to a flyer, slashing the asking rate and putting the Heat under the pump.
But Brisbane refused to hit the panic button and with a steady flow of wickets and slowing of the scoring rate, the Heat - led by consistent seamer Sammy-Jo Johnson (2-30) - dragged themselves back into the game.
Maitlan Brown (22 not out) and Georgia Wareham (17) showed pluck down the order but aside from Wyatt, too many Renegades batters failed to capitalise on promising starts.
Jonassen (1-27) was solid with the ball after she had been dynamic with the bat.