They will travel to either Macclesfield Town or Walsall, but it could so easily have been Rochdale.
Ben Clark scored the vital penalty as Dale missed one and had one saved.
Home keeper Dimi Konstantopoulos, who had been in brilliant form as Rochdale dominated the second half and extra-time, saved Alan Goodall's penalty, while Keith Barker blasted his over the bar.
Gary Jones and sub Callum Warburton scored for Dale, but Richie Humphreys, Willie Boland, Jon Daly and Clark netted for Pools.
It was Hartlepool who dominated first and the Rochdale defence was under long spells of pressure from the start.
After two minutes Matt Gilks saved well under the bar from a Michael Nelson header, and after eight he was in action again as he tipped a 25-yard shot from Eifion Williams over the bar.
Gilks palmed another long-range effort from Williams out as he seemed to be taken by surprise by the shot on 26 minutes, and two minutes later he escaped when Jon Daly turned well in the area to create a close-range chance, but prodded the shot wide.
Rochdale's only two first-half chances fell to Glenn Murray, but he blasted both of them high and wide of the target when he should have done better.
After the break the game changed totally, and it was Hartlepool's turn to be put under pressure.
Konstantopoulos made a brilliant triple save from Jones, Murray and Morike Sako and also tipped a Gary Brown shot round the post, while Willie Boland cleared an Adam Rundle corner off the home line when the big keeper was beaten.
Rochdale had more of the game in the second half than Hartlepool had in the first, and should really have gone through without the need for their penalty agony.
However, Pools can point to a string of good Gilks saves in the first half when they were on top and a goal then might have made the game so different.