The New Saints edged out Falkirk to set up a SPFL Trust Trophy final with Airdrieonians.
The only goal of the last-four tie came from Brad Young, who turned in a simple rebound after home goalkeeper Nicky Hogarth pulled off a stunning double save to deny Danny Redmond.
Despite having 12 shots, just two of which were on target, Falkirk struggled to test Connor Roberts in the away goal as they searched for a leveller.
The final takes place on 23/24 March.
TNS manager Craig Harrison: "We knew it was going to be tough, Falkirk are flying in their league. We kept the ball really, really well and took the sting out of the game."
TNS striker Brad Young: "We want to win everything we can. We've been pushing and pushing. I came here to win trophies and score goals, I'm over the moon with it."