Terry Butcher's side blew a two goal lead before Kevin Thomson and Jason Cummings - the double goal hero from Wednesday night's first clash at New Douglas Park - saw spot-kicks saved by Accies number one Kevin Cuthbert.
Veteran striker Jason Scotland had given the visitors a 12th-minute lead but the home side thought they had seen out a nervy 90 minutes.
However, in the fourth minute of stoppage time, Tony Andreu netted a shock equaliser to send the game into extra-time and ultimately penalties.
Thomson missed Hibs' first effort before four perfect attempts from Accies put the pressure on Cummings. Cuthbert read the 18-year-old's intentions though to spark wild celebrations as Alex Neil's team sealed their return to the top flight three years after being relegated.
Butcher made just one alteration to his side from the first leg as he opted for the experience of 26-year-old Danny Haynes over teenager Alex Harris down the right flank.
But the on-loan Notts County man lasted barely six minutes as a knee injury handed Harris a reprieve.
Accies player/manager Neil, meanwhile, resisted the urge to start himself in the biggest game of his coaching career.
But he did recall striker Scotland in place of Mickael Antoine-Curier after fitness issues limited the Trinidadian to an appearance of the bench in the first leg.
It proved a wise choice as the 35-year-old former St Johnstone and Dundee United hitman shattered the Leith side's fragile confidence with his early opener.
Ryan McGivern was casual with a ball out of defence and saw it intercepted by Ali Crawford. Jon Routledge then poked it to Scotland who rolled Michael Nelson far too easily before beating Ben Williams with a low drive.
Hibs did their best to respond immediately but were spurned when Paul Heffernan was called back for offside after rounding Kevin Cuthbert.
But there was another panic in the Hibs box when Darian Mackinnon set up Louis Longridge for another Hamilton chance. Williams stood up to block with his left foot, though, as Easter Road held its collective breath.
Hamilton's goal had made for a tense, yet compelling, affair with the home players seemingly gripped by the potential disastrous ramification of any slip-ups.
There was a nervousness about them and the jitters were hardly helped by the groans coming from their own fans every time they dithered on the ball.
There was no relief of the tension, though, when Cummings' got a head to Liam Craig's deep corner only for Routledge to rescue Accies' with a goal-line clearance four minutes before the break.
Andreu then fired into the side netting in first-half stoppage time while Scotland found himself crowded out by Williams inside the six yard box after the restart, but only after selling Craig and Nelson another clever dummy.
While they were not banging down the door, Accies remained in control as the game moved into the final stages.
When referee Willie Collum added on four additional minutes, Hibs thought they were nearly safe,
But again Nelson let Scotland wriggle past him before he teed up Andreu from eight yards out for the dramatic and deserved leveller.
Hibs had to find some courage from somewhere now and they almost rallied midway through the first half of extra time when defender Martin Canning allowed a long ball to run in behind him. Craig darted in but was tackled perfectly by the out-rushing Cuthbert 10 yards outside his box.
The scares kept on coming for the Easter Road side though when Andy Ryan tumbled to the ground after a challenge by Alan Maybury inside the Hibs area. But Collum called the fall a dive and booked the Hamilton sub.
With no scoring, Hibs' fate was to be decided by spot-kicks but again with fear in their eyes, it was the home side who blinked first when Cuthbert saved Thomson's opening effort.
Grant Gillespie, Andreu, Mickael Antoine-Curier and Scotland all netted for the visitors before Cumming's tired effort was turned away by Cuthbert again as Hibs' nightmare season ended in another disaster.