The two Yorkshire clubs have been neck-and-neck in the title race all season, with the Pirates going into the final weekend double-header one point ahead.
But the Steeldogs prevailed by following up Saturday’s 1-0 win on home ice with a 6-4 win in Hull last night.
Jason Hewitt's Hull side had gone into the weekend top of the standings after their 6-3 midweek win at third-placed Telford Tigers had edged them ahead of the Steeldogs, who had topped the table for the majority of the season.
On Saturday, a single powerplay strike from James Spurr in the 12th minute was enough to deny Hull and ensure that the title race went down to the final night.
A little under 24 hours later - in front of a sellout crowd - the two sides went at each other from the off, sharing 10 goals in a thrilling spectacle.
The Steeldogs found themselves 2-0 ahead after Ashley Calvert's powerplay strike at 6.20 was backed up by a Lloyd Gibson goal five minutes later.
But the Pirates came roaring back and were level by the first period break, Bobby Chamberlain halving the deficit at 12.11 before Lee Bonner equalised at 18.42.
Calvert's second at 22.48 restored the Steeldogs' lead, which was doubled again shortly after by Milan Kolena's effort.
But, as in the first, the home side were not giving up on their own title hopes easily and again dragged themselves leve, player-coach Hewitt making it a one-goal game just after the halfway mark before pouncing for a second time at 31.54.
Liam Charnock struck in the 37th minute to make it 5-4 to the visitors and, this time, there was to be no way back for the home side, their title dreams crushed further when Adrian Palak scored at 51.17.
Speaking afterwards, Steeldogs' player-coach Ben Moprgan said: "It feels a little surreal. people can say what they like about this league, but this league has been very, very tough.
"It's been an absolute slog. I have to give full credit to Hull - we've made the series between us over the course of the season one of the best."
Both sides will now turn their attention to the play-offs, Hull taking on Blackburn hawks, while the champions Steeldogs will face Billingham Stars.