St Kilda has qualified for the AFL finals for the first time since 2011 and shut the door on Greater Western Sydney's season with a 52-point thrashing at the Gabba.

Not since Ross Lyon was coach have the Saints tasted finals action and they clinched their berth via the 12.10 (82) to 3.12 (30) win, which could see them finish as high as sixth on the ladder.

The result confirmed the Giants — last year's beaten grand finalists — will not take part in the finals for the first time since 2015.

It was their third straight loss to finish off a season that promised so much and they could end up as low as 12th if Fremantle and Carlton register victories this weekend.

Needing to win big to have any chance of finishing in the top eight, the Giants had their chances in the first quarter but could only manage a 1.5 return.

The Saints made them pay for their errant ways, with Josh Battle and Brad Hill both slotting from tight angles to create the early buffer on the scoreboard, as Brett Ratten's side led by 10 points at the first change.

Toby Greene and Jack Riccardi kicked goals for the Giants in the second quarter to make it a three-point game approaching half-time, however the Saints gave themselves a degree of breathing space to lead by nine points at the main break.

But the Giants did not kick another goal after half-time, as their night turned ugly.

Awarded a messy mark as he dived forward, Rowan Marshall goaled for the Saints to start the second half, before Jack Lonie and Sam Billings skipped them out to a 29-point lead at three-quarter time.

Max King added his name to the scorer's list to kill the contest early in the final term before his teammates lined up in a seven-goal second half.

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Jack Steele finished with two goals for the match, in addition to posting 14 contested possessions, 10 clearances and seven tackles.

Jack Lonie also kicked two goals for the victors.

The Saints will finish the season in sixth place unless Collingwood beats Port Adelaide in Monday's final home-and-away match.

The Giants were dealt an early blow when Matt de Boer (back) was a late scratching, the tagger replaced by Isaac Cumming.

Recalled after being controversially dropped last week, Stephen Coniglio had 23 disposals for the Giants.

ABC/AAP