The Suns' captain kicked four goals, including three in the final term, to guide the home team to a shock 13.12 (90) to 10.17 (77) win.
Ablett sent the home fans into raptures when his second goal of the quarter put the Suns ahead but his best was yet to come.
The dual-premiership player stepped and fended his way through the Saints' defence, before sending a right-foot snap curling through the goal for his fourth major and a game-defining moment.
It was part of a remarkable best-on-ground display by the midfielder, who picked up a game-high 34 disposals.
The Suns' victory, their third in as many matches at their home ground after defeating Greater Western Sydney and Carlton at the end of last season, was secured through a gutsy second-half display as they made the most of a scrappy performance by an undermanned St Kilda line-up.Charlie Dixon and Luke Russell were the other multiple goal-kickers for the Suns, with Russell's second late in the fourth quarter a crucial settler after Steven Milne had closed the margin for St Kilda.
The Saints, led by captain Nick Riewoldt's two goals, had looked to have settled when they booted five-goals to none in the second-quarter to turn an 11-point first-quarter deficit into a 19-point halftime lead.
But the Suns bounced back with Ablett, Matt Shaw and teenage debutant Jaeger O'Meara kicking three third-term goals to move within two kicks of the lead at the last change.
From there the home team took control of the match through Ablett's inspiration and some St Kilda ill-discipline, the visitors conceding three 50m penalties and handing the Suns' their first two goals of the final term through free-kicks.
Late goals by Milne and Terry Milera gave the Saints hope of snatching a win but Aaron Hall's late breakaway major sealed the win and sparked celebrations.
Suns coach Guy McKenna made the claim after the match that Ablett is a better player than his father, Gary Ablett Snr.
He went on to suggest his captain's confidence in his young teammates was allowing the 2009 Brownlow Medallist to influence the game closer to goals.
“Gary's humble enough to say his old man is better than he is, I would beg to differ,” McKenna said.
“What we're seeing in Gary too is his leadership of understanding that he doesn't need to be in the middle now.
“That he has got the confidence and trust (of his teammates) ... his four goals clearly were telling.”
A disappointed St Kilda coach Scott Watters said his player's execution at key moments had proved the difference.
“From our point of view the effort was strong from the players, the efficiency was poor,” Watters said.
“You need both. You have to work extremely hard when you're not efficient.
“The players will be stung by that and they'll work hard to rectify it but obviously you lose a game on the back of it and that hurts.”
GOLD COAST SUNS 3.6 3.8 6.11 13.12 (90)
ST KILDA 1.7 6.9 7.14 10.17 (77)
Goals: Gold Coast Suns: G Ablett 4 C Dixon 2 L Russell 2 A Hall H Bennell J O'Meara M Shaw S Day. St Kilda: T Milera 3 N Riewoldt 2 A Siposs B Maister D Armitage J Steven S Milne.
Best: Gold Coast Suns: G Ablett C Dixon D Prestia J Harbrow J O'Meara R Thompson. St Kilda: J Geary D Armitage N Dal Santo L Hayes J Steven R Stanley. Umpires: Chris Donlon, Chris Kamolins, Andrew Mitchell. Venue: Gold Coast Stadium.