The revelation was made by Western Cape Director of Public Prosecutions, Rodney de Kock, during plea agreement proceedings.
"The deceased was murdered at the instance of her husband," he told Judge President John Hlophe.
In terms of the agreement, Hlophe sentenced Zola Tongo, 31, to an effective 18 years jail.
"The alleged hijacking was in fact not a hijacking, but part of a plan of subterfuge which Shrien Dewani, the husband of the deceased, and the accused had designed to conceal the true facts, to wit: that the deceased was murdered at the instance of her husband," said De Kock.
In a formal admission, handed in to court as part of the agreement, Tongo said he freelanced as a shuttle operator from Cape Town International Airport.
On November 12, he was waiting for fares at the airport when Shrien asked him to take him and Anni to the Cape Grace.
"After we arrived at the hotel, Shrien Dewani approached me alone and asked me if I knew anyone that could 'have a client of his taken off the scene'.
"After some discussion with him, I understood that he wanted someone, a woman, killed.
"He said he was willing to pay an amount of R15,000. Shrien Dewani said he had US dollars and could pay in US dollars."
'The female occupant had to be killed'
Tongo said later that day he spoke to a friend about arranging a hitman. The friend put him in touch with the other two men who have been arrested in the case. They met in Tongo's vehicle in Khayelitsha on the afternoon of November 13.
"We agreed that Shrien Dewani and I would be ejected from the vehicle and that the female occupant had to be killed."
He picked up Shrien and Anni at the hotel that night and took them to some "city sights", before going to the intersection in Gugulethu where the hitmen were supposed to be.
They were not there, so he continued in the direction of Somerset West where the Dewanis had supper.
"Prior to entering the restaurant, Shrien Dewani asked me what was happening and said he wanted the job done that night."
While the Dewanis were having supper, one of the hitmen called Tongo and confirmed they would be at the agreed location.
Don't forget the cash
Tongo said at one point in the vehicle, while he was driving around with the couple, he sent a text message to Shrien not to forget about the money.
Shrien replied by sms that the money was in an envelope behind the front passenger seat.
The hitmen were waiting as arranged at the intersection of NY112 and NY108, in Gugulethu.
They carried out the fake hijacking and drove for a short distance before ordering Tongo out of the vehicle.
"They then drove off with Shrien Dewani and the deceased still in the vehicle.
"I knew that [the hitmen] would not harm Shrien Dewani and that he would be dropped off at some further point. I also knew that the deceased would be kidnapped, robbed and murdered... after Shrien Dewani had been ejected from the vehicle in accordance with the plan."
The charges
Tongo is appearing in court on charges of murder, kidnapping and robbery with aggravating circumstances.
A section of the street outside the high court was closed to traffic while a heavy contingent of local and foreign press waited outside for proceedings to get underway.
Vinod Hindocha, Anni's father, arrived at court earlier. He was flanked by two men and sobbed as photographers shoved cameras into his face.
The matter is expected to start later than usual as a memorial service is being held for a retired judge who passed away recently.
Advocate Rodney de Kock is the prosecutor.
