Canterbury's dominance of the ITM Cup Premiership came to an end as Tasman ran out 26-6 winners in Saturday's semi-final meeting.
Tasman produced a stunning display in Nelson to topple the six-time defending champions and set up a showdown against fellow final debutants Taranaki, who overcame Auckland 49-30 earlier on Saturday.
Marty Banks played a pivotal role with 16 points from the boot as Tasman recorded a historic victory.
Tasman hit the front early through James Lowe who took advantage of a fortuitous bounce and won the race to the line, but Canterbury stayed in contention with two Tom Taylor penalties.
Banks slotted a couple of penalties of his own before halfback Jimmy Cowan scored on the stroke of half-time to give his side a 17-6 lead at the break.
Banks was the only player to trouble the scorers in the second half with three more penalties as Tasman repelled wave after wave of Canterbury attack while countering with customary flair and excitement.
Taranaki needed extra-time to oust Auckland in New Plymouth, with Waisake Naholo, Blade Thompson and Jackson Ormond all crossing in the additional period to wrap it up.
Manawatu will meet Hawke's Bay in the Championship final following a 23-18 success against Southland.
With Hawke's having booked their spot on Friday by beating Northland, Manawatu secured their berth after holding off a late Southland revival.