Mr Morgan said it was a “joke” that Ms Biles, who is the most successful US gymnast of all time, had decided to pull out of Tuesday’s (27 July) event for mental health reasons.
The decorated Olympic champion said she wouldn’t be taking part in the impending women’s team gymnastics final after obtaining the worst vault score in her impressive career.
So, what did Piers Morgan say - and has Simone Biles responded?
Here’s what you need to know.
Why did Simone Biles pull out of Olympics gymnastics events?
Ms Biles announced she would not compete in Tuesday’s women’s team final to focus on her mental health.
She said the decision wasn’t down to a physical injury but rather the pressure of expectation which was causing her mental health to deteriorate.
The four-time Olympic champion added she was worried she’d be leaving the Games “on a stretcher”.
Speaking of her decision, she said: “I don’t trust myself as much anymore. Maybe it’s getting older. There were a couple of days when everybody tweets you and you feel the weight of the world.
“We’re not just athletes. We’re people at the end of the day and sometimes you just have to step back.
“I didn’t want to go out and do something stupid and get hurt. I feel like a lot of athletes speaking up has really helped.”
On Wednesday (28 July) USA Gymnastics confirmed that Ms Biles would also not be competing in Thursday’s women’s all-around final.
In a statement, it said: “We wholeheartedly support Simone’s decision and applaud her bravery in prioritising her well-being. Her courage shows, yet again, why she is a role model for so many.”
What did Piers Morgan say about Simone Biles?
But Ms Biles’ decision, while gaining widespread support from the Olympic community, her fans and other sportspeople, appeared to provoke former Good Morning Britain host Mr Morgan.
He suggested that she had pulled out of the Olympic events due to “poor performance” instead of for legitimate mental health reasons.
Writing on Twitter, he said: “Are ‘mental health issues’ now the go-to excuse for any poor performance in elite sport? What a joke.
“Just admit you did badly, made mistakes, and will strive to do better next time. Kids need strong role models not this nonsense.”
Social media users were quick to criticise Mr Morgan’s comments, with some arguing that he was belittling mental health problems.
Others pointed out that he was once again targeting a prominent woman of colour for speaking candidly about mental health.
British DJ Jumpin Jack Frost posted: “Once again Piers Morgan has shown he has no respect for black women, going out of his way whenever he can to be nasty to any high profile black woman who struggle with their mental health.”
Mr Morgan, who left ITV in March, famously criticised Meghan Markle for sharing her experiences of having “suicidal thoughts” while a senior royal. He also slammed tennis star Naomi Osaka after she withdrew from the French Open due to struggling with depression.
The controversial journalist’s criticism of Ms Biles didn’t stop on Twitter.
He also penned a Daily Mail column about her decision, with the headline: “Sorry Simone Biles, but there’s nothing heroic or brave about quitting because you’re not having ‘fun’ – you let down your team-mates, your fans and your country.”
In it, Mr Morgan wrote: “You're not just at these Games for yourself, Simone.
"You are part of Team USA, representing the United States of America, and hundreds of millions of American people watching back home, not to mention all the sponsors who've paid huge sums to support you.
"And when you quit, you were performing as part of a gymnastics team, not yourself.”
Has Simone Biles responded?
As it stands, Ms Biles hasn’t directly responded to Mr Morgan’s criticism.
She simply posted a white love heart emoji to Twitter, with the post racking up more than 700k likes.
Ms Biles also retweeted myriad comments of support for her, including a Tweet from Today Show co-anchor Hoda Kotb which read: “Someone said it best. @Simone_Biles already won. She is a class act.
“Withdrew from team competition after vault... stayed and cheered on her teammates... got them chalk for their hands.. encouraged.. hugged them. She already won. Congrats on the silver medal!”
Another retweet read: “....did she cost the team a gold medal? or did her decision help her team win a silver medal? ….because if she had a really bad performance her team would not have placed at all.”