Both the Warriors and Tigers needed to win the game to remain in touch with South Australia and New South Wales on the Shield table, and it was an even contest right through the first three days.
WA came into the final day on 2-27 in the fourth innings chasing 256 to win with the highest score of the match being Tasmania's second innings tally of 286.
Despite WA losing Marcus Harris early in the final day's play for 18 when bowled by 21-year-old paceman Sam Rainbird, Marcus North and Adam Voges were putting the Warriors in the box seat with a terrific 135-run stand from the veteran pair.
However, when North fell for 79 and then Voges for 75 heading towards tea, WA were 5-203 and still needing 53 more runs to win with young pair Mitch Marsh and Ashton Turner new to the crease.
Marsh then was out shortly after tea for 18 caught at second slip off Ben Hilfenhaus after earlier being dropped by Mark Cosgrove for two with WA still requiring a further 36 to win.
Turner and Sam Whiteman, though were able to see the Warriors home without losing another wicket with Turner finishing 13 not out and Whiteman on 29.
The game was evenly poised but the pair managed to hit three boundaries from Hilfenhaus' final over to get the chase under 20 and then managed to cruise to 6-259.
The six points for the outright win moves WA to third on the Shield table on 20 points, four behind next week's opponent New South Wales and also Queensland.
Tasmania's hopes of making the final are all but over with the Tigers stuck on 10 points with one win, four defeats and two draws while 14 points off the top two spots.
North was named man of the match after top-scoring in both innings with scores of 87 and 79 while also taking the crucial second innings wicket of Ed Cowan for 59.
It continues a remarkable summer for the former Test batsman now leading the Shield with 759 runs at an average of almost 95 with three centuries plus a score in the 90s, 80s and 70s.