Opener Viv Narayan blasted 67 off 40 balls to spearhead Horspath's charge to a 55-run win over Aston Rowant in the Hartwell Trophy semi-final at the Recreation Ground.
Josh Richardson smashed 45 from 20 deliveries and Hussaan Ahmad struck 39 off 31 as the hosts kept up the onslaught to post an impressive 213-5 after choosing to bat.
Rowant also scored freely, but with wickets falling at regular intervals as Richardson took 3-37, the visitors ran out of steam to close on 158-8.
Now Horspath will face Oxford Downs in the final at Challow & Childrey on Sunday, September 15 as the side seek to go one better than the last two years, having finished runners-up to Banbury and Oxford respectively.
It will also be Horspath's seventh appearance in the final of Oxfordshire's premier T20 competition in 12 years, lifting the trophy when it was known as the Bernard Tollett Cup in 2013, 2014 and 2018.
Narayan got the innings off to a blistering start by hitting four boundaries off the first five balls, which allied to four leg byes, saw 20 runs come off the first over.
With Ahmad providing good support in a second-wicket stand of 83, he kept up the attack with three sixes as the side raced past 100 in the 11th over.
Narayan's superb knock, which also included nine fours, ended when he was caught by Elliot Matthews off Ben Knowler to make it 111-2.
But there was no let-up for Rowant with Richardson quickly into his stride with three cleanly struck straight sixes to both ends of the ground as Horspath continued to pile on the runs.
Ahmad and Richardson both fell to catches, but Charlie Turner, with 22 from 12 deliveries, maintained the momentum, before captain Amin Rafiq (21no) ensured the innings finished in style by launching two mighty sixes in the last over.
It had been a terrific display of hitting from Horspath and Rowant knew they needed a good start if they were to have any chance of challenging the target.
Ivan Lockem duly provided it as they stormed to 52-1 off five overs, but the combination of spinners Richardson and Ryan Hicks (1-27) applied the brakes.
Lockem had hammered three sixes in making 40 from 23 deliveries when he fell to Richardson with Tyron Eyles taking the catch, before Hicks ran down the pitch to claim a return catch from Yovaan Llangakoon inches above the ground.
With Richardson enticing skipper Chris North down the pitch and Lachlan Biggs completing the stumping, Rowant were suddenly 70-4 in the ninth over.
Matthews kept the visitors' hopes alive with 32 from 20 balls, but after he became Richardson's third victim at 107-5, the hosts were firmly in control.
It was left to Narayan (2-12) and Ahmad (1-17) to complete fine all-round games as the visitors fell well short and left Horspath looking forward to another final appearance.