The two vehicles collided at the intersection of Rakaia Gorge Road (State Highway 77) and Leaches Rd about 1.30pm on Thursday.
Police said one driver died at the scene while the other suffered minor injuries.
“The Serious Crash Unit and Commercial Vehicle Safety Team are investigating,” a spokesperson said.
The road was expected to remain closed for several hours and diversions were in place.
Hato Hone St John said they were notified at 1.31pm and sent a first response unit.
A spokesperson referred further inquiries to police.
NZ Transport Agency Waka Kotahi said SH77 was closed near Coleridge Rd.
Fire and Emergency shift manager Jill Higgison said crews from Hororata and Methven responded to a motor vehicle incident in Windwhistle, Selwyn.
-With NZ Herald