Winger Ben Loader scored two tries to send London Irish into the RFU Championship Cup final.
In-form Yorkshire Carnegie pushed the Exiles in the first half, but the hosts eased across the winning line after the restart to win 22-8 with Dave Porecki also crossing the whitewash.
The victory sets up a final showdown against Ealing Trailfinders in early May, after they overcame Cornish Pirates, with a date and venue still to be confirmed.
“Coming into the game we were putting a lot of emphasis on performance,” said match-winner Loader.
“But it’s always good to get into a final and give us a chance of silverware at the end of the season.
“I’ve been doing a lot of high ball work on the training ground and to have that come off and for me to reap the rewards is always good.”
A much-changed Irish side were on the back foot early on, but they were the first to score when Loader plucked a ball out of the sky and sprinted 35 metres to score in the corner with seven minutes on the clock. Fellow academy graduate Jacob Atkins added the extras.
But Yorkshire hit back to score midway through the first half when Greig Tonks was dispossessed, allowing Myles Thoroughgood through to score. The challenge on Tonks forced the full-back off and allowed a welcome return for Tommy Bell, who has been missing all season with an Achilles injury.
Carnegie then went 8-7 in front courtesy of a Jade Te Rure penalty, but that appeared to spark Irish into life with a second Loader score opening up a 12-8 half-time advantage.
When the two sides met in the league back in October, the Exiles cruised to a 72-5 thumping win, but it was a far closer affair this time around.
So it was a big moment on 49 minutes when hooker Porecki, the club’s leading scorer this season, crashed over for his 14th try of the campaign.
That is how the score stayed until a minute from time when Atkins kicked over a penalty to seal the win and a showdown with Ealing.
“Declan Kidney set us the challenge of winning the cup and the league at the start of the year and we’re in the cup final now,” said defence coach Declan Danaher.
“It’s a credit to the group of players who played. A lot of those guys have been getting their opportunity in the cup.
“They’ve put in a lot of hard work in the group stages, the quarter final and now the semi-final and it’s nice to get to the final, which is going to be a tough match.”
The Exiles host London Scottish in the league on Saturday (3pm).
LONDON IRISH: Tonks (Bell 21), Loader (Macken 76), Fowlie, Hepetema, McLean, Atkins, Steele (Brand 65), Reid, Porecki (Adams 75), Chawatama (Saulo 64), Maddison (c), de Chaves (Twomey 61), Northcote-Green, Gilsenan (Curtis-Harris 65), Treviranus.
Tries: Loader x2 (7,39), Porecki (49)
Cons: Atkins x2 (8,50)
Pen: Atkins (77)
YORKSHIRE: Elder, Watkins, Niko, Lucock (Bullough 40), Thoroughgood, Te Rure, Bruzulier (Wolstenholme 58), Thomas (Hill 45), Donnellan (Buckle 45), Nixon (Mitchell 50), Romaine (Bainbridge 57), Smith, Wilson (Kiri Kiri 50), Mayhew (c), Temm.
Try: Thoroughgood (21)
Pen: Te Rure (24)
Referee: Simon Harding
Attendance: 1,210
