The new Disney film will follow a family of elephants and their journey across the Kalahari Desert in Africa.
The show will be available to stream on Disney+ from April 3, three days after Harry and Meghan officially end their duties as senior royals.
In embarrassing video footage which emerged last year, Prince Harry was filmed pressuring Disney chief Bob Iger to give his wife voiceover work.
Pointing to his wife Harry quietly said: "You do know she does voiceovers?"
Iger, looking surprised, replied “ah I did not know that", before Harry continued: "You seem surprised, she's really interested".
The Disney boss spluttered: "We'd love to try. That's a great idea”.
In another clip, the Duke and Duchess were seen talking to the Lion King film's director, Jon Favreau.
Harry told him: "Next time, if anyone needs any extra voiceover work, we can make ourselves available.
Former Suits actress Meghan then said: "That's really why we're here – to pitch”.