The men went out on Monday near Fonoi Ha'apai and were expected back on Tuesday night.
Tonga police sought help from the New Zealand Rescue Co-ordination Centre and the United States Coastguard to try and locate the men.
The US Coastguard used a Hercules aircraft returning from a Search and Rescue conference in Auckland.
The plane found the boat last night and the men were rescued by a Tongan navy vessel early this morning.
