Counties scored another three tries through Reece Joyce, Roydon Gillett and Nicholas Wilson to lead 30-0.
The Lakers finally got on the scoreboard after 30 minutes thanks to one of this season's standout performers, centre Cam Walters. They worked their way into the Counties 20m before shifting the ball left. Walters received a cutout pass, stepped inside and crashed over to score and reduce the deficit to 30-4.
Counties hit back with a second try to centre Gillett to lead 34-3 at the break.
It didn't take long for Counties to score again in the second half as Michael Blucher scored an easy try against some weak defence under the posts.
The Lakers held Counties out for 20 minutes before Gillett breezed through a gap to secure a hat trick of tries. Counties led 46-4 with 20 minutes to play.
They extended their lead to 64-4 through tries to Rawhiti, Wilson and William Stowers before Bay of Plenty were put out of their misery by the fulltime whistle.
Bay of Plenty captain Johnson Peri said it was a "tough game".
"We knew it wasn't going to come easy. It was a huge effort for us just to get here, full credit to our coaching staff and management for the good work they do in a short time," he said.
Bay of Plenty forward Jeremy Siulepa was rewarded for an excellent campaign with a place in the New Zealand Residents team named to play the New Zealand Maori side this Saturday.
Meanwhile, defending champions Akarana Falcons secured their second successive Premiership title, defeating Waikato, 30-4.
Counties Manukau Stingrays 64 (Michael Blucher, Roydon Gillett 3, Nicholas Wilson 2, Reece Joyce, Buchanan Rawhiti 3, John Vuetibau, David Toetu, William Stowers tries; William Stowers 4, Buchanan Rawhiti, Stitiveni Taufa goals) Bay of Plenty Lakers 4 (Cameron Walters try)