Gold Coast overcame an early deficit to run over the Cats, with eight unanswered goals either side of three-quarter time setting up a 17.16 (118) to 11.12 (78) triumph, in front of 18,236 fans.
The victory lifts the SUNS to seventh on the ladder, while the Cats lose pace with the top three.
This was Ablett's fifth match against the Cats since heading north from Kardinia Park at the end of the 2010 season.
Despite being his usual ball magnet with 33 touches and a late goal, Ablett was overshadowed by Bennell who probably played the best game of his young AFL career.
Bennell was dogged by a hamstring injury in 2013 and a calf injury earlier this season, but looks set to fulfil the promise he showed in his breakout 2012 season.
As well as kicking a game-high six goals, he set up three other majors, including two of Charlie Dixon's three scores, and created countless other opportunities.
The result did not seem likely after a five-goal first quarter left the Cats 11 points in front, but they managed just six more in the rest of the game.
Almost as worrying for Geelong will be the ankle injury to Matthew Stokes who was forced off at the end of the first quarter.
One plus for the Cats was Shane Kersten who bagged three goals on his debut, one of which came from his first kick. Tom Hawkins and Steven Motlop also kicked three majors.
The SUNS' teenager Jack Martin, playing in only his second game after injuring his shoulder early on debut in the season opener against Richmond, showed why he is so highly touted in a 15-possession game, which also included seven tackles and a goal.
GOLD COAST 3.2 5.6 10.11 17.16 (118)
GEELONG 5.1 6.7 9.7 11.12 (78)
GOALS
Gold Coast: Bennell 6, Dixon 3, Russell 2, O'Meara 2, Harbrow, Ablett, Lynch, Martin
Geelong: Hawkins 3, Kersten 3, Motlop 3, Enright, Johnson
BEST
Gold Coast: Bennell, Ablett, Prestia, Harbrow, Dixon, Swallow
Geelong: Selwood, Duncan, Motlop, Kelly, Guthrie
INJURIES
Gold Coast: Matera (groin)
Geelong: Stokes (ankle)
SUBSTITUTES
Gold Coast: Luke Russell replaced Brandon Matera at half-time
Geelong: Josh Caddy replaced Matthew Stokes (ankle) in the second quarter
Reports: Nil
Umpires: Fisher, Kamolins, Findlay
Official crowd: 18,236 at the Metricon Stadium
