WA paceman Bryce Jackson snared 4-39 in a man-of-the-match performance as the Bulls were skittled for 131 in 29.2 overs on Sunday.
In reply, a WA side featuring mostly emerging players reached the victory target in just 26 overs, with Hilton Cartwright (33), Sam Fanning (26) and Jayden Goodwin (24) all chipping in.
The Bulls entered their last match of the regular season in third spot and well in the hunt to claim a spot in the March 1 final.
Queensland needed to beat WA and for Victoria to beat second-placed NSW to lock away a spot in the decider.
Even if NSW beat Victoria, Queensland could have still made the final by posting a bonus-point win over WA.
But things went awry for the Bulls from the outset.
Star trio Ben McDermott (six), Jimmy Peirson (four) and Matt Renshaw (two) all fell cheaply as Queensland slumped to 3-17 in the fifth over.
Lachlan Hearne (33) and Angus Lovell (18) briefly steadied the ship, but those knocks were only a temporary reprieve as WA's youth-laden attack continued to wreak havoc.
Queensland were 9-102 before No.10 Mitchell Swepson whacked 45 off 35 balls to at least give the Bulls some sort of chance to pull off a miracle win.
Jackson, playing just his fifth List A match, was the star of the show with four scalps, while Brody Crouch (3-45) and Mahli Beardman (2-22) were also influential.
The pace trio have just 15 List A appearances between them, and spinner Corey Rocchiccioli (0-19) was playing just his second List A match.
But despite their youth and inexperience, the WA attack ripped through Queensland's talented line-up with ease.Â
Swepson whacked three sixes and three fours in the sole real resistance Queensland were able to put up.
WA made light work of the run chase, with teenage paceman Callum Vidler (3-36) the only Queensland bowler to make any true inroads.
The win was only WA's second of the season, with their hopes of winning four straight titles derailed by injuries and poor form across the campaign.
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