The victory, their 11th in a row, gave Province the first ever SuperSport Challenge Trophy.
Coach John Dobson’s WP scored four tries in the opening half hour as the visitors struggled to adapt to the heavy underfoot conditions.
Winger Bjorn Basson bagged the first for the hosts after 15 minutes and a golden spell of three converted tries in the next 20 minutes all but secured the win for the home side.
Fellow winger Marcello Sampson scored a brace, with lock Jurie van Vuuren also getting with a nicely taken try under the sticks after some good interplay by his fellow forwards.
At 28-0 at the break, the hosts had the win all but in the bag.
Griquas never stopped playing though and in the second half showed why they made it all the way to the final.
WP lock JD Schickerling's 53rd-minute yellow card gave the visitors a gap as prop Nicolaas Oosthuizen scored their opening try, converted by replacement flyhalf, Andre Swarts.
A second try, this time by outside centre Koch Marx was another reward for the Kimberley side playing the numbers game and gave them more momentum into the last quarter of the match.
The visitors from Kimberley kept Province honest and making a game of it, with a late try to Tertius Kruger, again converted by Swarts, making it a nine-point deficit.