The Black Eyed Peas singer - who became pals with the British beauty this summer when the 'Parachute' hitmaker was the opening act on the group's tour - thinks her pal could soon work with some of the world's biggest movie and music stars.
She said: "She is such a good friend. But I don't think she has quite got her head around how big she is going to be. My girl really can rule the world. I have already heard crazy things like Robert De Niro wants to make movies with her and that Jay-Z wants to work with her."
Fergie even believes the Girls Aloud singer - who is rumoured to be joining the judging panel on the US 'x factor' when it launches next year - could reach the levels of stardom attained by pop superstars Madonna and Mariah Carey.
She enthused to the Daily Mirror newspaper: "Within five years we could be talking about Cheryl on the same level as we go Madonna or Mariah Carey."
Fergie has always been a strong supporter of Cheryl's, and pals recently claimed the bisexual star had told bandmate will.i.am - who was romantically linked to the singer after she split from soccer player Ashley Cole - she had more chance of sleeping with the 'Fight for This Love' hitmaker than he had.
A source close to Fergie - who is married to actor Josh Duhamel - said: "Fergie has been telling everyone she's more likely to sleep with Cheryl before will does.
"Everyone has been teasing him about his crush. But when Fergie came out with this, everyone fell about laughing.
"She's mentioned it a few times now. And even Cheryl thinks it's hilarious."