Judd Hall, who was 26, died when the driver of the car in which he was a passenger fled police while driving drunk on 24 January.
Jordan Nathaniel McGrath, appeared via video link in the Christchurch High Court on Tuesday morning and pleaded guilty to three charges, including manslaughter.
He will be sentenced in Greymouth on 7 July.
The victim's mother, Joe Hall, said she had spoken with McGrath and did not expect anything other than an apology.
McGrath knew that he had ruined many lives, and had accepted accountability, she said.
Joe Hall has lost four sons to tragic circumstances, including another fatal car accident involving a drunk driver.
Hear Joe Hall