The Heat beat the Melbourne Stars by eight wickets, overhauling their 87-run total with eight balls to spare in a final-round match reduced to 10-over innings by rain.
It meant they edged past the Strikers, who missed a chance to clinch the finals hosting rights when they lost by 13 runs to the Sydney Sixers earlier in the day.
Both the Heat and Strikers finished with 10 wins and four losses.
Earlier Melbourne Renegades (8-6) secured their spot in Saturday's semi-finals with a clinical 29-run win over Sydney Thunder.
Perth Scorchers are the other team in the semi-finals and they could finish as high as third, depending on the outcome of their final match against Hobart Hurricanes later on Sunday.