Keyhole also claimed first and second in the open men's division courtesy of Dune Kennings and Elliot Paerata-Reid.
"This is big for our club, we know our members back at Piha will be celebrating the win with us," said team captain Dune Kennings.
"We thought we were a chance for the title, but all the other clubs certainly gave us a big challenge," Kennings said.
"It all came down to the final tag team performance and those can go either way real quick but we did just enough to edge out Whangamatā and claim the title."
The lead in the final of the tag team seesawed several times across the 60 minutes with Whangamata Boardriders, North Wai from Christchurch and North Coast from Whangārei all sharing the lead at one point.
Keyhole held off both Elliot Paerata-Reid and Dune Kennings until their fourth and fifth riders and their dominant surfing pushed their team into the lead.
Whangamatā needed a 7.40 on their last ride with senior surfer Jos Kennings out in the water. He latched onto his last of three rides, a clean righthander, but came up short with a 5.37 handing the victory to Keyhole 54.47 points to 52.60.
Earlier Whangamata Boardriders challenged for the overall title thanks to wins by Ella Williams in the open women's division and Jos Kennings in the over 40 men's division.
Surfers compete for their club across standard heats and the exciting tag team format to find an overall club champion.
2021 Hurley National Club Championships overall team rankings, Whangamatā, Saturday, May 8:
1 Keyhole Boardriders
2 Whangamata Boardriders A
3 North Wai Boardriders
4 Lion Rock Boardriders
5 North Coast Boardriders
6 Waihi Beach Boardriders
7 Hawke's Bay Boardriders
8 Whangamata Boardriders B
