EVO-STIK League Premier Division leaders Farsley were too strong for East Division side Belper Town, winning 3-1 thanks to goals from Luke Parkin, James Spencer and Ben Atkinson.
Trafford pulled off a bit of an upset at Shawe View as they beat Premier Division side Buxton 1-0.
Adam Farrell’s goal 13 minutes from time was enough for the West Division side to book their place in the final.
Farsley last reached the final in 2015, when they lost on penalties to Warrington Town at Stockport’s Edgeley Park.
They won the competition back in 2006, beating Stocksbridge Park Steels 1-0 at their own Throstle Nest home, while it is Trafford’s first ever appearance in the final.
The date and venue for the final will be confirmed shortly.
Meanwhile, there was success for NPL clubs in their respective county cups in midweek.
Marske United beat Middlesbrough’s Under 23 side to reach the final of the North Riding Senior Cup, where they will play EVO-STIK League Premier Division outfit Scarborough Athletic.
Nantwich Town beat Stockport County 3-0 to reach the final of the Cheshire Senior Cup, where they will play Runcorn Linnets, and Stafford Rangers beat Kidsgrove Athletic to reach the final of the Staffordshire Senior Cup.