Shaking off the humiliation of their 112-point loss to the Power only last month, the Swans won 14.11 (95) to 8.11 (59) after a dominating display across four quarters at the SCG on Friday night.
The minor premiers, who earned a standing ovation from the 44,053-strong crowd, will play the winners of Saturday's Geelong-Brisbane preliminary final in the decider at the MCG on September 28.
It is the first time John Longmire's men have defeated the Power since 2016 and comes after their round-21 drubbing at Adelaide Oval.
"It's a great spot to be in. It's what you work for," Longmire said.
"We executed today as good as we could have. Our method was really good.
"We were strong in the contest. We concentrated on our process and lived in the moment and got the job done."
Tom Papley was busy again for Sydney, kicking an equal team-high three goals. (Dean Lewins/AAP PHOTOS)
Meanwhile, Port coach Ken Hinkley was left with another post-season flop.
Hinkley holds the unwanted record as the VFL/AFL coach with the most games coached without reaching a grand final, having tasted disappointment in three previous preliminary final losses in 2014, 2020 and 2021.
He is contracted until the end of next season.
"They deserve the win. They deserve to play next week," Hinkley said.
"We'll accept that they were the best team in the competition and finished on top of the ladder for a reason.
"We knew we were going to have to be absolutely at our best and we just weren't capable of going with them tonight."
The Swans could be without defender Dane Rampe for the grand final after the stand-in captain, in his 250th game, collected Power midfielder Zak Butters high in the first quarter.
Butters did not suffer a concussion and finished the match with 20 disposals.
Forward Logan McDonald (two goals) could also be forced out of the decider with an ankle injury after a collision with Miles Bergman in the final term.
The Power received a downfield free kick following this incident involving Dane Rampe and Zak Butters.— AFL (@AFL) #AFLFinals | #AFLSwansPower pic.twitter.com/ZBpJ6UMCEGSeptember 20, 2024
Sydney hero and 200-gamer Isaac Heeney (two goals, 24 touches) was typically influential despite close attention from Willem Drew, well-supported by star on-ballers Chad Warner (two goals, 21 touches) and Errol Gulden (27 touches).
Luke Parker played a crucial role in nullifying Port defender Aliir Aliir, while Joel Amartey and Tom Papley did the heavy lifting on the scoreboard with three goals each.
Jason Horne-Francis was the standout for Port with 23 disposals and seven clearances, but struggled to lift his team.
Port's semi-final star Jase Burgoyne slotted the first goal of the game courtesy of a free kick paid against Nick Blakey for an off-the-ball bump, but Jake Lloyd and Amartey replied in quick succession to put the hosts ahead.
Leading 4.0 to 2.3 at quarter time, the Swans built a 33-point margin before electric Port forward Willie Rioli hit the scoreboard.
Rioli earned another opportunity to eat into the deficit after the siren but his set shot went wide for a behind, with Port trailing by 25 points at the main change.
McDonald has been subbed off with Robbie Fox the replacement. — AFL (@AFL) https://t.co/ywWx6atlJ7September 20, 2024
Port struggled to mount a second-half challenge when a full-throttle Warner slotted a goal in the opening 40 seconds of the second term.
Warner then kicked his second of the evening after intercepting a poor kick in front of goal from Travis Boak to build a 40-point lead.
Boak and Port skipper Connor Rozee slotted two unanswered goals in the final term but the damage had already been done.
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