The crash happened on State Highway 5 between Tarukenga Marae Rd and Oturoa Rd about 11.17pm.
Jason Barnes, owner of the relocation company Prestige Building Removals, said the man, who died at the scene, had crashed into one of the pilot vehicles before ending up underneath the truck carrying a house bound for Cambridge.
Barnes said his team did "everything in their power" and there was nothing more they could do to help save the man.
"The guy just didn't want to stop".
They had just picked up the house from Ngongotahā near Rotorua. There were also four pilot vehicles, two at the front and two at the back of the moving truck.
He said the team had just started the job when the man had driven up at speed, hit one of their pilot vehicles then crashed into the truck carrying the house.
The driver of the moving truck was "very shaken up" and had refused to get out of the cab of the truck, Barnes said.
He had told Barnes "I think the man is dead."
The pilot vehicle drivers had jumped to action, ringing emergency services and trying to help the man, who was unresponsive, he said.
They were not sure whether the man had suffered a medical condition or something of that nature. The situation was "heartwrenching" and it was devastating that "someone will be without a family member this Christmas", he said.
Counselling and support were being provided for the staff involved and he said they had been given the option to take as much time off as they needed.
People dealt with stress in different ways and sometimes would say they were okay when they really were not, he said.
"I am really proud of them and how they handled it."
He said many members of the house moving industry had reached out to help where they could and were also providing support at this time.
The client whose house was involved was also "very understanding" and was far more worried about everyone involved, he said.
"Our full condolences go out to the family of the man."
Rotorua road policing manager Senior Sergeant Simon Sinclair told the Rotorua Daily Post the driver was an elderly man and was the only occupant in the car.
The man's next of kin were still being contacted and his name would not yet be released.
Sinclair said the Serious Crash Unit attended the scene and were investigating but it appeared the driver of the car was heading east towards Rotorua while the truck and house were travelling west. They have collided head-on, coming from opposing directions, he said.
WorkSafe had been notified and was making initial inquiries to establish what their next steps might be, a Worksafe spokeswoman said.
