Now he will meet either title favourite John Higgins or his semi-final opponent Paul Hunter in his bid to become the first Welshman to capture the title since Doug Mountjoy defeated Stephen Hendry in 1988.
Victory was a sweet moment for the world No 26 after losing to Hendry in last year's UK semi-final at Preston. He recovered from 4-2 down in the afternoon session to inflict upon the Stoke-on-Trent based Harold only his fourth defeat in 19 matches this season.
But it was touch and go for Stevens and his greatest supporter, dad Morrell, watching the action unfold in the wings at the International Centre.
He squared the first session at 4-4, went 7-5 and 8-6 in front only for Harold to recover to 8-7. The 31-year-old from Staffordshire looked poised to level at 8-8 when he led 60-0. Instead, he was forced to play a safety shot and eventually Stevens cleared up with 72 to win on the pink.
It was defeat number two in a ranking tournament semi-final this season for Harold, who also lost to David Gray in the Benson and Hedges Championship final earlier this month.
"I'd trade all these semi-finals and finals to win one of these events," Harold said before picking up pounds 19,750 as consolation.
"I knew as soon as Matthew got to the yellow he was going to clear up. I just under-screwed the black and had to play safe otherwise I would have made it 8-8."
Stevens, the 1996 B and H Champion, is now guaranteed pounds 39,000, double his previous biggest payday since turning pro in 1994 and should Hunter get the better of Higgins the final will be a battle between two stablemates. They are members of `Wheels in Motion' managed by wheelchair-bound Geoff Faint.
"I don't mind who I play, I'm just looking forward to my first final," said Stevens.Reuse content