The singer, who is rumoured to be pregnant with her and Liam Payne's child, looked radiant during the TV segment.
The 33-year-old wore a black jumpsuit that managed to conceal her growing 'bump', although eagle-eyed fans were quick to notice that Cheryl, who sat with her hands in front of her tummy, went to great lengths to hide her stomach.
Cheryl with Childline founder Esther Rantzen and Chris Hoy
"Cheryl keeps hiding her tummy definitely a bump there come on girl show it off!" wrote one exasperated fan, while another commented: "Cheryl is definitely pregnant, sitting very still on the one show."
Some went as far as to point out that presenters Matt Baker and Alex Jones were in on the secret.
"Alex keeps looking at Cheryl's bump #theoneshow announce the happy news," tweeted one viewer. "Matt and Alex desperately trying not to mention Cheryl's bump... #TheOneShow," joked another.
Fans noted how Cheryl was hiding her tummy
Cheryl, who was speaking about her new role as an ambassador for Childline, certainly had a glow about her. Her fans commented on how beautiful she looked, with one posting: "Pregnant or not Cheryl Cole looks fab! Happy and healthy."
During The One Show the new Childline advert was also played, which showed Cheryl concealing her figure in a loose-fitting jumper. The former Girls Aloud singer voiced young people struggling with personal issues, including sexual assault.
The singer made a radiant appearance on The One Show
"Thousands of people are suffering with problems just like these," she says in the clip. "I want to make sure anyone going through a hard time, knows they can talk to someone and get the help they need. Childline is there for you, whoever you are."
The I Don't Care singer filmed the advert back in September. At the time her PR team tweeted a snapshot, showing a photo of the Geordie beauty that had been cropped to not show her tummy.