Rioli is back from an ankle injury for his first game in almost a month, with the Hawks also regaining fellow star forward Lance Franklin from suspension.
They dropped Matt Spangher and Jed Anderson.
The Cats, who lost in-form forward Paul Chapman to suspension and dropped Taylor Hunt, regained Josh Caddy from an ankle injury.
They also included youngster Jordan Murdoch for his first game since round 21.
Murdoch kicked three last-term goals to help the Cats overcome the Hawks in the two teams' most recent meeting in round 15.
He's played just three AFL games since.
Hawthorn coach Alastair Clarkson said Rioli trained well on Tuesday to demonstrate his readiness to return, but might be used as the sub because of his lack of match fitness.
"That's a possibility," the Hawks coach said.
The Cats remain without injured star small defender Corey Enright.
Spearhead Tom Hawkins, who has missed two of Geelong's past five games with the back injury that has nagged him throughout the season, has been named despite lingering fitness concerns.
Potential replacement Shane Kersten is an emergency.
Sydney plumped for speed, adding Ben McGlynn and Gary Rohan for Saturday night's preliminary final against Fremantle in Perth.
They replace injured pair Kurt Tippett (knee) and Tom Mitchell (ankle).
McGlynn, who missed last year's premiership win with a hamstring injury, returns from a calf problem, while Rohan was recalled after being dropped for last weekend's semi-final win over Carlton.
Coach John Longmire said McGlynn had been close to selection against the Blues but was definitely right to go this weekend.
"We ruled him out last week even though he was touch-and-go, but that hopefully gives him the opportunity to come in and have a really good strong contribution this week against Fremantle," Longmire told the club's website.
Utility Lewis Roberts-Thomson, who played his first game since injuring a knee in April with Sydney's reserves side last weekend, was named an emergency.
The Dockers have made one change, regaining All Australian defender Michael Johnson from a calf injury, replacing Tom Sheridan.
"We obviously know the year that he's had," Dockers football manager Chris Bond said of Johnson.
"He plays a very important part of our back six and he's up against some real quality opposition as well, so he's a very important in for us."
HAWTHORN (to play Geelong)
Backs: Stratton Lake Guerra
Half-backs: Burgoyne Gibson Birchall
Centres: Smith Mitchell Hill
Half-forwards: Breust Franklin Gunston
Forwards: Puopolo Roughead Rioli
Followers: Hale Sewell
Interchange: Lewis Bailey Whitecross Shiels
Emergencies: Spangher Anderson Cheney
In: Franklin Rioli
Out: Spangher Anderson
GEELONG (to play Hawthorn)
Backs: Rivers Lonergan J Hunt
Half-backs: Mackie Taylor Bartel
Centres: Kelly Selwood Stokes
Half-forwards: Christensen Vardy Motlop
Forwards: Podsiadly Hawkins Caddy
Followers: Blicavs Duncan
Interchange: Corey Guthrie Murdoch Varcoe
Emergencies: T Hunt Kersten West
In: Caddy Murdoch
Out: Chapman (suspended) T Hunt
FREMANTLE (to play Sydney)
Backs: Johnson Dawson Duffield
Half-backs: Spurr McPharlin D Pearce
Centres: Mundy Crowley Mzungu
Half-forwards: Ballantyne Mayne Fyfe
Forwards: Clarke Pavlich Walters
Followers: Sandilands Barlow
Interchange: Sutcliffe Neale Suban de Boer
Emergencies: Sheridan Hannath Silvagni
SYDNEY (to play Fremantle)
Backs: Rampe T Richards Biggs
Half-backs: McVeigh Grundy Smith
Centres: Everitt K Jack Malceski
Half-forwards: Hannebery Bolton Bird
Forwards: Parker Pyke White
Followers: Mumford Kennedy
Interchange: Cunningham Jetta McGlynn Rohan
Emergencies: B Jack Lamb Roberts-Thomson
In: McGlynn Rohan
Out: Tippett (knee) Mitchell (ankle)