After bowling Perth out for 99, the Sixers cruised to their target with 31 balls to spare at Adelaide Oval.
The Sixers defeated the Scorchers in last year's final and now have two wins in three WBBL tournaments - they were beaten grand finalists in the first edition.
Chasing their small target, Sixers openers Alyssa Healy and captain Ellyse Perry ensured a trouble-free victory.
The pair put on 36 runs from the initial five overs to set the tone of a partnership which reaped 64 runs from 10.1 overs.
Healy was dismissed for 41 from 32 balls while Perry (36 not out) hit the winning runs, with Ashleigh Gardner not out 22.
Earlier, the Scorchers stumbled with the bat against a miserly Sixers bowling attack headed by Sarah Coyte.
Coyte, who only returning to top-level cricket last weekend after almost a year off while battling anxiety, took 3-17 from her four overs.
Spinner Erin Burns claimed 2-26 while Perry, Sarah Aley and Kim Garth were the other wicket takers.
The Scorchers collapsed mid-innings when they lost four wickets in four consecutive overs.
From 0-23, Perth slumped to 4-41 with their chief run scorers this tournament failing to fire - captain Elyse Villani made 16 and her opening partner Nicole Bolton five.
Heather Graham (14) and Thamsyn Newton (12) tried to arrest the slide before No.8 batter Piepa Cleary top scored with 18 not out.