Barrett and Bay of Plenty first five Chris Noakes exchanged a salvo of penalties to have the sides 6-6 midway in the first half until Bay of Plenty wing Lelia Masaga broke the game open with two tries in the space of two minutes.
The first came in the 23rd when the powerful runner finished off a well-constructed team try, the move switching from flank to flank to stretch the Taranaki defence before reaching Masaga.
The next was a fine solo effort, Masaga poaching the loose ball after Taranaki wing Jackson Ormond made a hash of a high kick by halfback Jamie Nutbrown.
That took the score to 20-6 in a blink of an eye but Barret punished Bay of Plenty indiscipline with a stream of penalties, one from 50 metres to keep his side in the running at 20-15.
Fortune swung Taranaki's way when referee Glenn Jackson, fed up with blowing penalties, sin-binned Bay of Plenty flanker Sam Cane.
With halftime looming, Taranaki halfback Tyson Keats found a gap in a counter-attack and flicked the ball out to outstanding openside flanker Scott Waldrom who conjured a magical back flick to put rampaging No 8 Samuela Vunisa for a try which tied the scores 20-20 at the breather.
With Cane still in the bin, Taranaki scored their second try within minutes of resumption through fullback Kurt Baker after Waldrom and Jayden Hayward combined to prise Bay of Plenty's defence open.
Two more Barrett penalties followed as Taranaki dominated the forward exchanges in which hooker Mahonri Schwalger was impressive before Bay of Plenty, restored to their full complement, answered with a Dan Waenga penalty.
But Barrett popped over his record ninth three-pointer to take the score out to 39-23.
With Taranaki tiring, Bay of Plenty clawed their way back into the game but it was not until Waldrom was sinbinned with a handfull of minutes left that they scored two tries through Lance MacDonald and Cane who atoned for his earlier sin-binning.
An under-manned Taranaki then tackled their hearts out to keep Bay of Plenty at Bay for the remaining three minutes of "last-play" time that Jackson allowed.
- NZPA