Mziwamadoda Qwabe was given a 25 year prison sentence for his involvement in the murder of Anni Dewani after he promised to cooperate with prosecutors, officials said today.
Part of Qwabe's plea agreement requires him to testify against other people accused in the case, including Mrs Dewani's husband, Shrien.
Mr Dewani is accused of hiring Qwabe and Xolile Mngeni - who still faces charges - to kill his new wife while they were on their honeymoon in Cape Town.
A British court heard last week that Mr Dewani needed a year to recover from depression before he would be able to face extradition proceedings.
He has been diagnosed with severe post-traumatic stress disorder and severe depression, and his lawyers argue that his health and life will be at risk if he is extradited to South Africa to face trial.
Mr Dewani, from Bristol, is due at Westminster Magistrates' Court on September 18 when the chief magistrate, Howard Riddle, will be given an update on his condition.
Mr Dewani claims he and his wife were hijacked while travelling in a taxi through Cape Town in November 2010. While he was ejected from the vehicle, Mrs Dewani was later found murdered in the abandoned taxi.
He was allowed to leave South Africa before the taxi driver, Zola Tonga, claimed the newlywed had offered him 15,000 rand (around £1,200) to arrange the killing and make it look like a carjacking.
More top news
"Our ability to pre-empt or respond to threats will be eroded if we don't keep up with our adversaries."
"You are one of the silence breakers and we all owe you a debt of gratitude."
Maximum temperature 11 C (52 F).