The Wanderers took full advantage of a strong wind and slight slope in the first half to build up a 29-3 lead scoring five tries in the process.
It was one-way traffic as their powerful pack denied their opponents any good ball and No 8 Owain Thomas, lock Aaron Canter, prop Joe Russell, scrum half Rhys Griffiths and flanker Evan Phillips scored tries and centre Mike Hurley converted two against a Scott Taylor penalty.
St Joseph’s flanker Jason Cox then scored a solo try but the Wanderers added further tries by Lewis Wilkie and Rhys Force with Hurley converting both, though brave St Joseph’s rallied and wing Will Rowlands and centre Aiden O’Dare touched down plus a conversion by Taylor.
Wanderers skipper Liam Mackay received the cup from former Cardiff centre Steve Crandon, now an accounts manager with Molson Coors.
* The Worthington Mid District Cup Final will be played between Merthyr and Bargoed at Sardis Road, Pontypridd on Wednesday, May 20 and promises to be one of the best-ever matches in this fine competition’s history.
In the semi-finals Merthyr defeated Nelson by 49-21 at Abercynon, while Bargoed beat Division One East champions Penallta by 31-0 at Caerphilly.
The final will be more exciting following Merthyr’s shock win at Bargoed in the Championship which was the only league loss of the season thus far by Bargoed, who have already won that title.