Castletown will face Michael United in the final of the Paul Henry Gold Cup, following their respective victories in the semis yesterday.
Despite probably starting their match against double winners Colby as underdogs, Town produced a strong display to see off their southern rivals 3-1 at Glen Road.
The went in 2-0 up at half time thanks to goals from Alex Crawley and Steve Ward.
Colby pulled one back through Mark Costello but Brett Allcote restored Town's two goal cushion
In the other tie Michael United overcame Pulrose 2-0.
They were two up at half time after Chris Hancocks and Paul Corlett found the net and kept it tight in the second to seal their place in the final.