As revealed by Lions coach Chris Fagan earlier in the week, Brisbane recalled 31-year-old ruckman Darcy Fort to replace the injured McInerney, who twice dislocated his shoulder during last week's 10-point preliminary-final win over Geelong.
The inclusion of Fort is Brisbane's only change, with star midfielder Lachie Neale named despite battling an ongoing heel injury.
Sydney go in unchanged after Mills' hopes of a fairytale return were crushed on Wednesday.
Swans forward Logan McDonald, who was subbed out of his team's 36-point preliminary-final win over Port Adelaide with a left ankle injury, has recovered in time for the grand final.
The unchanged line-up means utility Robbie Fox has held his place for the decider.
Mills injured his hamstring at training on September 10, just three days after Sydney's qualifying-final win over GWS.
The Swans were not willing to risk Callum Mills in the AFL grand final. (Dan Himbrechts/AAP PHOTOS)
The 27-year-old said he trained "100 per cent" on Wednesday and declared he was physically ready to play in the grand final.
But just hours later coach John Longmire and the club's medical staff decided not to take the risk, with Mills not even named as an emergency when the teams were unveiled on Thursday evening.
"Really difficult for Millsy, no question about that," Longmire told Swans media.
"He did everything he needed to do at training, trained absolutely flat-out.
"But then when we sat down without the emotion of it and looked at it and thought the challenges of getting through four quarters was always going to be there and had to make the tough call.
"It was a tough one for him, but hopefully best for the team."
Another player who will be wistfully watching on this Saturday is Sydney midfielder Taylor Adams.
Adams missed Collingwood's grand-final win over Brisbane last year due to a hamstring injury.
A move to Sydney was meant to spark a fresh chapter for Adams, and he played 19 games during the regular season.
Taylor Adams has missed out on a spot in the Sydney Swans' squad for the AFL grand final. (Bianca De Marchi/AAP PHOTOS)
But the 31-year-old's waning output resulted in him being dropped for the qualifying final against GWS.
Like Mills, Adams was also a notable omission on Sydney's emergency list.
Aaron Francis, Peter Ladhams and Caiden Cleary have been named as Sydney's three emergencies, while for Brisbane it is Darragh Joyce, Henry Smith and Harry Sharp.
Dane Rampe will captain Sydney in Mills' absence.
Fort, who was overlooked in six consecutive national drafts, has played just 35 AFL games since making his debut for Geelong in 2019.
He notched 18 games for the Lions in his first season at Brisbane in 2022, but only seven matches last year and two appearances this season.
Lions midfielder Josh Dunkley is backing Fort to produce a strong effort against Sydney ruckman Brodie Grundy.
"We have full trust in Darcy Fort that he's going to come in and play a role for us and do a tremendous job," Dunkley told AFL360.
"He's been chipping away in the reserves for such a long period of time and been nearly best on ground every week.
"It's great that he gets an opportunity.Â
"Oscar will be sorely missed. I feel like there is a hard-luck story every year, and that's our one this year. Hopefully we can do it for him."
