GWS have stormed into an AFL semi-final, just 12 months after finishing 16th, with a classy 24-point win over St Kilda at the MCG.
The Giants booted eight straight goals from midway through the first quarter to late in the second term to blow Saturday's elimination final wide open.
St Kilda twice managed to come back from more than 40 points down, even cutting the margin to just 19 points early in the last term.
But GWS' early lead was too much for the Saints to overcome as the Giants ran out winners 15.11 (101) to 11.11 (77) in rookie coach Adam Kingsley's first final in charge.
The No.1 defence in the AFL during the home-and-away season, St Kilda, in their first final in Melbourne since 2011, gave up a score of more than 100 for just the second time this year.
GWS' total was their second best at the MCG in club history, just falling short of the 103 they scored in a loss against Melbourne in 2013.
The Giants will meet Port Adelaide in an away semi-final next Saturday night.
GWS slumped to 3-7 midway through the season, but have now won 11 of their past 14 matches to have won a final in all of the club's six post-season campaigns.
"Just so pleased for our people, our staff, our players - so much hard work has gone into the season," Kingsley said.
"Towards the end of the season, when we were up and going pretty well, I thought it was possible (to win a final).
"It's a hard one to answer because I did have that inner belief, right from the pre-season that that we had a really strong group.
"We just didn't necessarily show it in the first 10 rounds of the season."
After finishing third-bottom during a difficult campaign last year when long-time coach Leon Cameron departed, the Giants drew on their experience of making a grand final in 2019 and playing in two post-season games in 2021.
Josh Kelly had a final to remember, finishing with 27 disposals and two goals to be the most influential player on the ground.
Tom Green (36 possessions) and Lachie Whitfield (31) also enjoyed plenty of the ball as GWS had more drive out of their midfield than St Kilda.
Saints captain Jack Steele stood tall with 38 possessions, while Max King (three goals) and Cooper Sharman (two) both had threatening periods up forward.
The result ends a promising first season for Ross Lyon in his second stint as St Kilda coach.
"I'm disappointed for all the club, and the players," Lyon said.
"We had an opportunity, we didn't take. There's no excuses. They (GWS) just got it done in the contest and on the spread.
"I thought we've got more in us than that, but you can only play as well as your opposition let you."
Both teams were hit by late withdrawals just before the sudden-death final.
St Kilda were first, announcing the omission of Tim Membrey because of a personal health matter.
The experienced forward had been poised to line up in attack alongside fellow tall Max King for only the third time this season.
An hour before the bounce, star GWS midfielder Stephen Coniglio was pulled out after suffering an eye injury at training during the week.