The deal is believed to have been done after Harry cornered the company’s boss Bob Iger at the premiere of The Lion King in London last year.
Disney sources said the release had been long planned to coincide with Earth Month, which begins next Wednesday and was not changed because of the coronavirus pandemic. The film will raise money for the charity Elephants Without Borders.
The Sun reports that sources say the arrangement is another indication of where the couple see their priorities going forward.
The royal insider explained: “For Meghan, this type of work is going to be coming out of Hollywood going forward.
"She feels comfortable there around her people and has projects already planned like her children’s book.”
The Sussexes left the $21.5 million mansion they were borrowing in Vancouver and took a flight out of the city shortly before US President Donald Trump and Canadian PM Justin Trudeau closed the border between their countries.
The couple landed in the LA area, which includes Bel Air — the posh neighbourhood of 1990s Will Smith sitcom The Fresh Prince of Bel-Air.
Royal courtiers believe the decision to move full-time to the US makes a mockery of the couple’s earlier pledge that they chose Canada because they wanted to live in a Commonwealth country.
One said: “We are stunned and horrified. The country is going through a traumatic event at the moment. They have a beautiful cottage in Windsor where they could have based themselves.
“It’s just a stone’s throw away from where the Queen and Prince Philip are in self-isolation.
“Prince Charles and Prince Andrew are both out of action too for very different reasons.
“This was an opportunity for them to put country before their own interests. California isn’t going anywhere.”
The Sun first revealed Harry and Meghan’s plan to quit the UK in January.