A source told MailOnline that Harry flew to Heathrow on Sunday, where he changed to a connecting flight to Johannesburg.
It comes as Harry and Meghan, who are living in California after quitting royal duties in 2020, are set to return to Britain in September to support “several charities close to their hearts”.
The visit comes amid ongoing tensions between the Sussexes and the royals, while the Duke’s memoir is looming.
The Royal Family has been bracing itself for Harry’s forthcoming tell-all book, which he has vowed will be an “accurate and wholly truthful” account of his life.
The tome was expected to be published in late 2022 but a release date has yet to be confirmed.
There will be concern in royal quarters that Harry will delve into his rift with his older brother Prince William, his troubled relationship with his father Prince Charles, his view of his stepmother Camilla and the Megxit fallout.