Speaking to the Daily Star, Gary quipped: 'I think Robbie will make a brilliant dad - he's got the mind of a nine-year-old!'
The X-Factor judge, himself a dad to three children, Daniel, 11, Emily, nine, and Daisy, two, added that, 'In all seriousness though, he's great.'
Robbie said last year that he does not think he is mature enough to have kids, claiming that when he sees mums and dads playing football in the park with their children, or pushing prams, it just makes him think he is 'knackered as it is'!
He also claimed that whilst his wife wants babies, the thought 'terrifies' him!
Gary meanwhile has earned his cool stripes with his family, revealing his little ones are chuffed about him being on TV - despite not having shown any interest in his career beforehand!
'My son sits playing Nintendo all the way through my concerts, they're not mad about what I do,' says Gray. 'But being a judge on X Factor, they couldn't believe it.
'They are absolutely loving it.'
Can you see Robbie Williams ever becoming a dad?