Emergency services rushed to Nullica, about 10 kilometres south-west of Eden, about 4.10pm yesterday after the collision on Towamba Road.
The boy was pronounced dead at the scene while the man in his 30s driving the ute and two passengers, girls aged eight and three, were taken to hospital.
The younger girl was airlifted to Randwick Children’s Hospital and the man to a hospital in Canberra, both from Merimbula Airport.
The older girl was taken by road to South-East Regional Hospital at Bega.
The truck driver, believed to be in his 50s, was also taken to the Bega hospital for mandatory testing and treatment for shock.
Officers from the Southern Region Crash Investigation Unit were sent to investigate.
Part of Towamba Road near the Princes Highway remained closed early this morning.