An early Andy King goal settled any nerves Steeton may have had and he doubled their advantage before half-time.
Graham Holmes then sealed his side’s progress to the last four, where they will face Humber Premier League side Goole United.
Bay Athletic missed out on meeting fellow County Amateur League club Ovenden West Riding in the other semi after bowing out to West Yorkshire Association Premier Division outfit Fields.
The tie finished 2-2 – Kieran Ryan and Danny Stocker netting for Bay, with Danny Cunningham and an own goal replying – but Bradford-based Fields won a penalty shoot-out 5-4.
League action saw Campion maintain third place in the Premier Division with a 2-0 home win over bottom side Hall Green United.
The first half was goalless but it took Steve Hollingworth just moments to break the deadlock after coming on as part of a double substitution, with Omar Habeeb sealing the points late on. Salts took a valuable point off second-placed Kirkburton as it finished 2-2.
Substitute Richard Magson came on for the last 15 minutes and equalised for Salts, adding to Sam Waterhouse’s earlier strike, while Jordan Tindall and Jack Greene replied.
Ovenden West Riding remain top and are now three points clear after beating Huddersfield YMCA 2-0 with goals from John Booth and Carlton Pownall.
Hunsworth extended their advantage at the Division One summit to seven points after crushing Tingley Athletic 10-3. Andy Wood bagged a hat-trick, backed up by two goals each from Lee Brooke and Sam Morton.
Overthorpe, who have occupied the basement position for most of the season, gave themselves a chance to stay up as Steve Jordan and James Wilson scored in a 2-1 home win over Campion Reserves.
The Dewsbury-based club are now level on points with the reserve sides of Salts and Storthes Hall and just two behind another trio of rivals.
West Horton, without a game since before Christmas, showed their lack of match practice as Steeton Reserves won 2-0 to move above their hosts on goal difference. Ross Bailey and Casey Dowthwaite supplied the firepower.
Dudley Hill Rangers, with just two league games left to play, moved to within four points of promotion out of Division Two after drawing 2-2 with Golcar United Reserves thanks to two Roman Zurek goals.
Second-placed Thornes nicked a 2-1 home win over Ovenden Reserves, while DRAM Community kept up the pressure at the top with an 11-1 drubbing of Littletown Reserves.