DR RANJ revealed the culture of "bullying" on This Morning after slamming the show as "toxic" earlier this year.
The star, who quit the ITV show in 2021, opened up about his experience as a regular contributor in the new documentary Imposter Syndrome: Dr Ranj Singh.
It comes as main presenters Holly Willoughby and Phillip Schofield departed this year amid reports of a rift and are set to be replaced by two new stars.
Speaking in the documentary, Dr Ranj said: "For me, it was the culture that had developed, in many ways about the way people were being treated and being made to feel, and it wasn't good for people's mental health.
"I felt bullied at times.
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"And, you know, I was a mental health ambassador, anti-bullying ambassador on this channel, whose job it is to look after people.
"It's my job to say something and say, 'Look, things aren't quite right and now we need to do something about this.'"
Asked if he had spoken to Phillip and Holly since he quit, he responded: "Not for a long time, we wouldn't really have that kind of relationship."
Dr Ranj quit This Morning two years ago and The Sun later revealed he made complaints about staff behaviour behind-the-scenes.
Then, in a social media statement, he said his complaints led to him being fazed off the show.
“I was on the show for ten years and I genuinely loved and valued working there,” Dr Ranj said.
“However, over time I grew increasingly worried about how things were behind-the-scenes and how people, including myself, were being treated.
“I didn’t know the truth about what was going on with Phillip, but I do know the issues with This Morning go far beyond him. It takes more than one person to create a culture.
"So I did what I thought was right ... I then found myself being used less and less.”
Dr Ranj continued: “I even took my concerns directly to the top of ITV.
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“The culture at This Morning had become toxic, no longer aligned with ITV values, and I felt like because I whistle-blew I was managed out.”
The Sun has contacted This Morning for comment.
Last night The Sun told how Ben Shephard and Cat Deeley have secured big money deals to become This Morning's new main presenting duo.