Mooney made a scintillating 105 off 73 deliveries to power the Scorchers to 3-172 at Allan Border Field.
The Heat, who dropped crucial catches in the field, were all out for 149 in 19.1 overs.
Wicketkeeper Mooney finished the match as she started it with a brilliant direct hit at the non-striker's end to run out Nicola Hancock.
Scorchers opener Mooney, who started her WBBL career with the Heat, was at her composed best from the get-go.
She was particularly severe on the leg side initially where she flicked several deliveries to the fence with consummate ease.
Mooney brought up her half-century off 42 balls without breaking stride before upping the ante in an innings that included three sixes.
A straight six off Jess Jonassen was sublime, as was a ramp to the boundary off Nadine de Klerk that went straight over wicketkeeper Georgia Redmayne's head.
She took to the first over of the power surge, flipping a six off Nicola Hancock in an over that went for 21 runs.
"I probably just went through different phases. I was hitting it really nicely early and then was trying to hit it a little bit hard through the middle and then came good towards the end," Mooney told AAP.
"In those innings you have to hang in there when it is getting a bit tough. I thought Brisbane bowled really well, Lucy Hamilton in particular in the surge.
"It just showed if you bowled in the right areas it was tough to score. We managed a decent score and held them off at the end."
Mooney received outstanding support from opening partner Katie Mack (31) in an 89-run opening stand.
Mooney was dropped on 32 by Charli Knott when she splayed a drive towards third man.
Mack was put down at slip by Annie O'Neil first ball off Lucy Hamilton and then again by Knott at short fine leg when on 19 from the bowling off Jess Jonassen.
English import Paige Scholfield (22) came to the crease and continued the momentum.
In reply, the big-hitting Grace Harris - playing her first match of the campaign for the Heat after recovering from a calf injury - made 46 off 30 balls before being bowled.
Jonassen was then run out without scoring in a horrible mixup with Knott (32) and it was 4-84.
It was always going to be a bridge too far from there despite big hitting from West Indies powerhouse Chinelle Henry (39 off 23).
In the end it was Mooney who owned the match at a venue she knows so well.
11°C