Geelong's 13.18 (96) to 12.8 (80) victory sets up a mouth-watering preliminary final next Friday night against arch rivals Hawthorn, who are minor premiers but have lost their past 11 clashes with the Cats since the 2008 grand final.
Port, who rose from 14th in 2012 to win an elimination final and then go so close against the Cats, are eliminated.
Geelong veteran Paul Chapman kicked a game-high four goals but was reported for rough conduct after a high bump on Port's Robbie Gray during the third term and could be in doubt for the preliminary final depending on the match review panel's findings.
"Who knows? I didn't hit him high. I'm not sure if I did or not," Chapman told Triple M in a post-match interview when asked about the incident.
Midfielders James Kelly, Joel Selwood and Steve Johnson were influential for the Cats who have qualified for the their sixth preliminary final in seven years, while Justin Westhoff kicked three goals for Port and skipper Travis Boak was dominant.
Port controlled the first half but were outscored 10 goals to five in the second half.
Chapman scored the first two goals of the game but Port fought back to lead by a goal at quarter-time. The Power booted four goals to Geelong's one in the second term to hold a 23-point advantage at halftime, 7.5 (47) to 3.6 (24).
Westhoff kicked two second-quarter goals and small forward Angus Monfries was a constant threat for Port, the unfancied seventh-placed side in their first finals series since 2007.
Finals-hardened Geelong ramped up their intensity in the third term, kicking 5.6 to Port's solitary goal to lead by seven points at three-quarter time.
Geelong jumped out to a 23-point lead at the 21-minute mark of the final term with a goal to Selwood but two late goals to Port kept the tension high before a final goal to Geelong's Steve Motlop, his second.
Big forward Tom Hawkins also kicked two goals for Geelong.
Geelong coach Chris Scott said the Cats needed to make some structural adjustments before the start of the second half.
"They had free players everywhere," he said.
"In the second half, to turn that around and play some of our best footy, is a really exciting thing for next week."
Scott said the Hawks were in the box seat for their preliminary final clash after having a rest this weekend.
And Geelong's 11-game winning streak against Hawthorn was no comfort.
"Who cares who the pressure's on? It's nil-all at the start of the game," Scott said.
First-year Port Adelaide coach Ken Hinkley said he was proud of his side's season but admitted they may have panicked during Geelong's third-quarter onslaught.
"We knew the Geelong surge was going to come at some stage," Hinkley said.
"We possibly felt the heat. I suppose we were probably waiting for it a little bit and when it came we didn't quite handle it as well as we'd like.
"They stepped it up when they needed to. That's why they're a great side."
GEELONG 2.2 3.6 8.12 13.18 (96)
PORT ADELAIDE 3.2 7.5 8.5 12.8 (80)
Goals: Geelong - Chapman 4; Motlop, Hawkins 2; Christensen, Bartel, Corey, Selwood, Duncan. Port Adelaide - Westhoff 3; Schulz 2; Monfries, Ebert, Hartlett, Broadbent, Lobbe, Gray, Logan.
Best: Geelong - Selwood, Chapman, Kelly, Johnson, Motlop, Stokes, Bartel. Port Adelaide - Boak, Broadbent, Westhoff, Cornes, Gray, Monfries, Carlile.
Umpires: Matt Stevic, Simon Meredith, Shane McInerney.
Official Crowd: 52,744 at MCG.