Fonua-Blake made his debut against the Parramatta Eels in Round 7 and was chosen in the New Zealand train-on squad for the recent Four Nations tournament.

Manly coach Trent Barrett said Fonua-Blake would be a key part of the Manly forward pack next season.

"The contract extension is a good reward for Addin. He still has a lot of hard work to do, but we were happy to extend his deal," he said.

"Addin is a big skilful player who gives us plenty of muscle up front. He is doing really well and we are pleased to have him with us."

Fonua-Blake said he was grateful for the opportunities he has received at the Sea Eagles.

"I am really enjoying playing at Manly. The extension gives me a chance to further develop my game by working with experienced forwards like Martin Taupau and Nate Myles," he said.