Television pictures showed 34-year-old Dewani making his way from his flight to the terminal at London's Gatwick Airport, and then being whisked away in a vehicle in the early morning, pursued by photographers.
Dewani arrived in Britain before sunrise on a connecting flight from Dubai, having left Cape Town on Tuesday, a day after the high court there cleared him of hiring hitmen to murder 28-year-old Swedish citizen Anni Dewani (nee Hindocha) in a Cape Town township during their honeymoon in November 2010.
Police escorted Dewani through Cape Town International Airport to catch an Emirates flight heading to Dubai Tuesday afternoon. He reportedly flew first-class and later switched to a flight to London.
Prosecutors said Dewani wanted his wife killed because he is gay and felt trapped into marriage by family pressures.
Dewani told the court in a written statement at the start of the trial that he is bisexual and admitted having sex with male prostitutes, but said he loved Anni.
Anni's family said after the acquittal that they planned to sue Dewani, saying she would never have married him if she had known about "his secret sex life with male prostitutes".
"Neither would we have, as a family, condoned a union with a man who indulged himself in such a sordid manner," the family said in a statement.
Both families are of Indian origin and mothers, fathers, brothers and sisters had sat across the courtroom from each other since the trial began in October.
The judge in the case, Jeanette Traverso, said the state's evidence had "fallen far below" the level needed to secure a conviction.
She said testimony by two men jailed for Anni's murder that Dewani had masterminded the plan was "improbable" and full of contradictions and lies.
Dewani had returned to Britain within days of the murder and fought a three-year legal battle to avoid being extradited to South Africa, claiming he had mental health problems, including depression and post-traumatic stress.
But he was sent back to South Africa in April, where he was found fit to stand trial and was held at a psychiatric hospital for the duration of the trial.