Thornensians will take on Wetherby in the final of the Yorkshire Silver Trophy on Sunday after beating Goole 26-14 in their semi-final at Coulman Road last weekend.
Thorne did much of the hard work in the first half and led 21-0 at the break.
After half time, though, local rivals Goole hit back.
But Thorne did enough to hold on to their lead and book their place in the final against league rivals Wetherby, who beat them to the Yorkshire Three title.
No 8 Rob Moffatt touched down early in the match to put Thorne ahead, and winger Rob Brown was on target with the conversion.
Prop Aden Smith was next to touch down, Brown again adding the extras, as he did following a try from second row Tom Hughes which put the home side into the lead at half time.
Goole hit back shortly after the resumption of play with prop James Walton and centre Oscar Sugden both having tries converted by stand-off Richard Barrass, but that was to be as close as Goole would come to taking the lead.
With the match coming to an end, Aden Smith scored his second try to make it 26-14 in Thorne’s favour.