The Dublin side included former Premier League players Johnny Behan and Pete Madsen, but could not match the 2015 champions.
Winning coach Tim O’Halloran savoured the triumph as many had written off his side.
“Many people felt Killester were stacked but we play at national level every week and I felt after the opening quarter we had their measure.”
The winners are no strangers to upsetting the odds, as O’Halloran explained: “We went to Killorglin in the quarter-final and it was supposed to be just a case of them turning up and, although it took two periods of extra-time, we managed to do the business.”
Killester coach Tom Doherty was stunned by the defeat. “I have to admit we came to Cork and expected to win but credit to Demons they showed class from start to finish as their outside shooting murdered us.”
Demons will play Maree in the final after the Galway outfit survived a magnificent Fr Mathew’s comeback to win the other semi-final 84-80.
Maree were 16 clear with just six minutes remaining in the final quarter when Mathew’s found another gear but their stirring comeback fell agonisingly short. Winning coach John Finn said: “It was a strange game as we looked home and hosed but Mathew’s gave us a mighty fright.”