Dewani was put on a flight to Cape Town from Heathrow yesterday to face a charge for ordering the contract killing of his wife Anni, which he denies.
"Shrien Prakash Dewani, 34, has today, on 7 April, at approx. 20:00 hours (local time) been extradited from the UK to South Africa," a Scotland Yard statement confirmed on Monday.
He was taken from Fromeside Hospital, a secure mental health unit in the British city of Bristol, to the airport by officers from the Metropolitan Police Service Extradition Unit.
The officers were met at the airport by representatives from the South African authorities who have escorted him on the flight to South Africa.
Dewani was originally arrested by officers from the extradition unit on December 7, 2010 at the request of the South African authorities.
He will be taken directly to the court soon after landing in Cape Town.
The move came three years after a protracted legal battle to keep the Bristol-based businessman in the UK.
Dewani's lawyers had argued that he should not be forced from the UK to face trial until he had recovered from mental health problems, including depression and post-traumatic stress disorder.
But in March, judges at the High Court in London rejected all his grounds for appeal against his removal from the UK and denied him the chance to take the case to the Supreme Court.
It is expected that Dewani will be treated at the Valkenberg hospital while awaiting trial, and South African media have reported that security at the facility, where a number of notorious criminals are held, has been beefed up in anticipation of his arrival.
His initial assessment will be for 30 days but an agreement between the British and South African authorities will see the businessman returned to the UK in 18 months if deemed unfit to stand trial.
Dewani is accused of ordering the murder of his 28-year-old wife Anni in November 2010, who was shot as the couple travelled in a taxi through the Gugulethu township while they were on honeymoon.
Prosecutors allege South African national Xolile Mngeni, who was later convicted of premeditated murder and jailed for life, had been hired by Dewani to kill his wife.