Wing Fu Cheung, 65, also known as Nelson Cheung, was attacked and stabbed near Randalstown in Janurary 2015.
Christopher David Menaul, 25, originally with an address in Barra Street in Antrim town, also pleaded guilty to wounding Mr Cheung's wife.
He admitted stabbing her in the hand and robbing her.
A defence barrister asked Belfast Crown Court that his client be re-arraigned on the three charges he had previously denied.
The barrister also asked the judge to adjourn the tariff hearing on Menaul's life sentence.
Adjourning the hearing to determine the minimum term that Menual will have to serve, the judge told him that the law provided only one sentence for murder - life.
A previous court hearing was told that on the night of 7 January, 2015, Mr Cheung and his wife, Winnie, were driving to their Ballymena home.
They had just left their Chinese restaurant in Randalstown and, as they drove along the Caddy Road, their car was "rammed'' by another vehicle.
A prosecution lawyer said that after Mr Cheung got out of the passenger seat he was confronted by two males and was stabbed up to 18 times.
It was also claimed that he was hit with such force, one stab wound "went straight through his body and out his back''.
Portuguese national, Virgilio Agusto Fernando Correia, 35, with an address in Grant Avenue, Randalstown, County Antrim, is accused of Mr Cheung's murder and the attack and robbery of his wife, as is engineer Gary Thompson, 34.
Mr Thompson, who is now living at a PSNI approved address, is also accused of wounding, assisting offenders, handling stolen goods, and perverting the course of justice.
His 34-year-old wife, Lisa Thompson, who is also living at a PSNI approved address, faces a series of separate charges.
She denies assisting offenders, handling stolen goods, and perverting the course of justice.
A County Antrim man has been jailed for life after pleading guilty to the murder of a Chinese businessman almost two years ago.