The documentary follows the journey of African elephants on an eight-month trek across the Kalahari Desert.
For The Times of London's Ed Potton, the former Suits star traded "pomp and circumstance for schmaltz and cheesiness”.
"The silken tones that Meghan employed on the legal series Suits and which were often muzzled during her time as a full-time royal are now given free rein," Potton wrote.
"And yes, she certainly has an actor’s way with a phrase and a likeable sense of mischief. ‘Oh! Who did that?’ she coos in mock disgust when one of the elephant calves breaks wind. The sense of performance, though, often feels overegged. Even the underwhelming moment in which the elephants rip some bark off a tree is presented like the announcement of the winner for best picture."
Elephant was directed by Alastair Fothergill, Mark Linfield and Vanessa Berlowitz, who all reportedly worked on director David Attenborough's Planet Earth.
Overall, Potton said Elephant serves as a hint that "evidence-based nature documentaries" may be a thing of the past, as the Meghan-lead documentary "feels a bit shallow”.
Meanwhile, Variety critic Owen Gleiberman called the theme of Elephant "rather dry" for a flick intended to shed light on the species' risk of ivory poaching.
Gleiberman described Meghan's narration as "an inviting version of the wholesome but amused Disney narrator singsong”.
Empire's Ian Freer said her narration came off as “overeager to please" with dramatisations. Freer said, though, that the Duchess managed to stay on "the right side of annoying”.
Film critic Robbie Collin of The Telegraph called Meghan a "fine fit" as the documentary narrator, stressing that the documentary is geared toward a young audience.
"If you're homeschooling at present, consider your Friday morning's activities taken care of," Collin, who gave the doc three stars, wrote.
Elephant will begin streaming on Disney+ on April 3.
It’s understood Meghan accepted the voiceover gig in return for a donation to Elephants Without Borders, a non-profit organisation in Botswana that aims to protect the species from poaching.
In a video obtained by the Daily Mail, Harry is seen approaching Iger about Meghan doing voiceover work. "You know, she does voiceovers," Harry could be heard saying to Iger, 68, as the prince pointed to his wife.
"Oh really, I did not know that," Iger said.
"She's really interested," said Harry.
"We'd love to try," Iger responded.
Elephant will serve as her first entertainment gig after she and Harry announced their plans to step back as senior members of the royal family. The couple will no longer hold an official office at Buckingham Palace as of today, April 1.
This article originally appeared in Fox News and was reproduced with permission.