The Take That singer is said to have filmed a cameo appearance for the BBC sitcom starring Miranda Hart, according to The Sun.
The episode in question will reportedly see Miranda and her mother (Patricia Hodge) attempting to seduce the X Factor judge.
A source said: "He has already filmed his scenes. The cast were thrilled he took part."
However, TV insiders have also hinted that Simon Cowell may not be pleased with Barlow appearing on the BBC so close to the X Factor final on ITV.
"Simon will want all the focus on The X Factor, so he might not be too thrilled to know Gary is also on BBC One," an insider claimed.
Miranda will return for a third series on BBC One later this year.
A movie spinoff is rumoured to be in the works following the completion of the third series.
Watch a clip of Miranda Hart talking to Digital Spy below: