Mr Pohiva's Democratic Party won 14 out of the 17 seats.
Kalafi Moala said it was a remarkable and unexpected feat, given the Pohiva administration's tenure was cut short by the August dissolution of Parliament.
The King called the snap election over concerns about the government's conduct.
Mr Moala said despite this Mr Pohiva's brand remains strong.
"He has declined in terms of numbers but he's still the most dominant politician that's influenced politics in Tonga," he said.