Defending 137, leg spinner Sarah Glenn (4-31) was brilliant with the ball and returned her best figures in Scorchers colours.
The English import opened the bowling and struck twice in the first over, dismissing Grace Harris and Jess Jonassen for ducks to give Perth the perfect start in the field.
The Scorchers had the Heat at 5-87 with a little over five overs remaining, however Laura Kimmince hit 40 from 17 deliveries to be the match-winner for Brisbane.
Earlier, stand-in skipper Beth Mooney was superb with the bat, she posted a match-high 49 before falling to a sublime one-handed diving catch at point.
Mathilda Carmichael was also pivotal in helping the Scorchers to a competitive total, with a valuable 35 from 23 deliveries towards the end of the innings.
After two nail-biting losses, Perth will have a couple of days to regroup before weekend matches against the Hobart Hurricanes and Adelaide Strikers, with a spot in the WBBL|06 finals still within their grasp.
After the match Sarah Glenn said;
“A few early wickets put us in good stead but we know how strong their batting line up is.
“We’re disappointed, but we’ve got a couple of days to regroup and refresh and we know there are still plenty of positives to take from today.
“It won’t affect us too much; we’ll just be ready to go for the last two games.”