The home was where the couple spent their final period as working royals before moving to north America, and last month they extended the lease on a 12-month rolling arrangement, The Sun newspaper reported.
Frogmore, a Grade-II listed property owned by the Crown Estate, was a gift from Harry’s grandmother the Queen and is reportedly being used by Princess Eugenie and her husband who are said to be out of the country.
The Sussexes will be joined by their children, three-year-old Archie and Lilibet who turns one on Saturday, and their visit to mark the Queen’s Platinum Jubilee celebrations has sparked rumours the couple will have their daughter christened with the monarch present.
It will be the first time the duke and duchess will have brought Lilibet, who was named in honour of the Queen, to the UK and the couple are expected to attend the thanksgiving service on Friday marking the monarch’s 70-year reign.
There is further speculation the Duke and Duchess of Cambridge are moving to the area to be closer to the Queen and potential schools for their children.
Harry and Meghan have established a new life for themselves in the celebrity enclave of Montecito in California, buying a multi-million pound home and launching a non-profit foundation.
The couple have also signed lucrative deals, thought to be worth well over £100 million, with Spotify and Netflix that have given them the capital to pursue their new lifestyle and public goals.
With the Queen expected to pace herself over the four-day bank holiday weekend, extended so the nation can celebrate the jubilee, there is speculation she will not travel to Epsom racecourse for the Derby on Saturday as she does not have a runner, although another of her thoroughbreds is entered in a race.
The day could be the perfect opportunity for the royal family to gather to celebrate the christening of Lilibet at Windsor Castle on the child’s first birthday.
A Buckingham Palace spokesman declined to comment on the reports and said: “Frogmore Cottage remains the UK home of the Duke and Duchess of Sussex.”