The Black Eyed Peas frontman, who is currently on tour with the 26-year-old singer, also revealed that he is "happy looking after her".
He told Now magazine: "Her mum's great. She can totally trust me with her daughter. Cheryl's a good family girl and her mum's been her rock through all that happened so I think [she] wanted to make sure I was a good boy.
"Her mum approves of me, I've been told. She knows I've been helping Cheryl through all this and just trying to keep a smile on her face."
The star added: "She's a beautiful girl but she's a good girl and beautiful inside as well. I'm happy looking after her at the moment.
"She's a strong girl but everybody needs somebody to look out for them, and that kind of looks like it's my job."
