The TV star, whose comedian husband Iain Stirling provides the ITV2 dating show's voiceover, began hosting it for the 2020 winter edition and then took over on the main show from the late Caroline Flack.
But Rachel Finni, who took part in the 2021 series of Love Island, spoke to Murad Merali's YouTube channel about her time on the show and criticised Whitmore's casting.
Finni, 29, said: "I'm kind of gutted Laura Whitmore is hosting it though, I thought we'd get a Maya Jama or AJ Odudu.
"The benefits you get from being married to the narrator, ‘cause she’s not a great host."
However, the comments didn't go unnoticed by Whitmore, 36, who slammed the accusation that she got the job because of Stirling in fan questions on her Instagram stories.
She said: "I’m not going to give too much energy to it because there's always stuff like this and you kind of just brush it off but I think we need to be careful when we discuss women and their work.
"I've worked in telly for 14 years. I won a competition to be the face of MTV and have stayed working from job to job.
"I’ve done incredible things all over the world, I’ve worked with the best teams, but I've never got a job because of a guy I dated."
Whitmore and Stirling welcomed their baby daughter in March 2021, who travelled with her to the Love Island set that year.
In Finni's interview, she also claimed that Love Island was fixed, that she had been bullied by other contestants in footage that wasn't shown, and that she had been brought in to tick a diversity box with no thought to who she could be matched with.
Watch: Laura Whitmore brands Love Island reunion show 'awkward'