They will play Dundee side Grove Menzieshill in the final and the clash is a repeat of the play-off final after the Tayside team beat under-strength Edinburgh University 6-1.
Robbie Shepherdson opened the scoring for the Division One and play-off champions and No.2 fell to Duncan Riddell.
Western pulled the contest back to 2-2, but Jacob Tweedie netted to put Grange in front and Dan Coultas scored for 4-2.
Western responded in the second-half and pulled the score back to 4-3 before Coultas put the Capital side 5-3 ahead.
Further goals from Frank Ryan, Alan Johnston and Cammie Fraser made it 8-3.
Edinburgh University women’s bid for a domestic double continues as they made for the Scottish Cup final, where they will play Dundee Wanderers, who defeated Erskine Stewart’s Melville 3-0 in the other semi.
Uni secured their place with a 2-0 win over rivals Watsonians thanks to goals from Kathryn Meenan and Sophie Maunder.