Coach Francis Vakadranu was happy with his side's performance and said they had prepared well in the two-weeks leading up to the tournament.
"It's good to defend the title," he said.
"It's always a tough game in the finals eh? We played them in the pool and it was easier, but come finals it's a different ball game."
Taihape started the final with the lion's share of possession but couldn't find a way out of their own half.
Midway through the half Ngamatapouri finally got their hands on the ball and shot out to a 12-point lead.
But with two minutes left in the half, a yellow card had Ngamatapouri a man down, creating space for Taihape to score a length of the field try on halftime.
The teams traded two tries each in the second half, Taihape never allowing Ngamatapouri to put the game away.
Vakadranu said it was pleasing to get the win and credited Taihape for pushing them in the final.
"Sometimes size doesn't matter. It's the heart and in the last few minutes they started coming back.
"But the boys played together as a team and gelled together as a team."
In the playoff for third, Kaierau beat Utiku Old Boys 19-12.
Meanwhile, Wanganui opened the women's provincial tournament with a 19-14 win over Wellington Black.
The home side, which had been cobbled together at the last minute, impressed coach Lesley McKenzie despite going down to strong Hawkes Bay (34-12) and Taranaki (28-12) sides in their remaining two games.
"Really pleased and surprised," McKenzie said. "A lot of them just met each other today."
It was a good way for the team to test itself in quality competitive games, she said.
It would be up to the players as to whether they wanted to enter the Central Region qualifiers but McKenzie expected they would.
Manawatu won the women's title, beating Hawkes Bay 35-19 in an entertaining final.
