All-rounder Johan Botha took four wickets as Warwickshire were skittled out for 110 to give Northants a 40-run victory at Edgbaston.
The South African claimed 4-16 after the visitors had reached 150-8 with Alex Wakely hitting 35 off 22 balls.
Northants tail-enders Jack Brooks (33) and David Willey (22) put on a record-equalling ninth-wicket stand of 59.
Tim Ambrose top-scored for Warwickshire with 25 before being dismissed by Andrew Hall, who took 3-18.
Botha's haul was the off-spinner's best figures in a Twenty20 match, with two of his wickets coming in his first over on a slow pitch in Birmingham.
Northants had been in danger of being dismissed for under 100 when they limped to 91-8 before Brooks and Willey's late resistance, which equalled that of Lancashire's Glen Chapple and Peter Martin at Leicester in 2003.
Northants coach David Capel told BBC Radio Northampton:
"When you lose as many wickets as we did in the first 15 overs it was a tremendous performance.
"That partnership between David Willey and Jack Brooks was absolutely outstanding. From that position we fancied as soon as we got up to 140 it would be a competitive total on that surface.
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