The Warriors won by 84 runs, Michael Hogan clean-bowling three of the Tigers' tail to claim 5-37 and lead his side to their second outright victory of the season.
Only Alex Doolan (75) looked like getting Tasmania near their target of 250, set when WA were dismissed for 187 in their second innings.
Shield champs Tasmania have suffered three outright losses in their past four games and head into the Big Bash League break with their title defence in disarray.
The Tigers have failed to pass 200 in their past three innings, making 164 against NSW last match and 196 in the first innings against WA.
They were 7-41 in the first innings against the Warriors before all-rounders Evan Gulbis and Luke Butterworth saved them with a partnership of 145.
Their second-innings chase began poorly when Mark Cosgrove (4) was caught behind at 1-5.
They steadied as Doolan took control and were well in it at 3-130 before losing 7-35.
Doolan hit 12 fours but looked unimpressed with being given out caught behind to Ashton Agar (2-20) at 6-152, virtually signalling the end for the home side.
Earlier, WA all-rounder Mitch Marsh helped his side recover from a second-innings 4-32 with a patient 70.
The highly rated 22-year-old's score added to five wickets for the match and four first-class 50s already this season.
Tasmanian captain and wicketkeeper Tim Paine bagged 10 dismissals in a match for the first time.