Charlton, 72-years-old, has said that the city would handle World Cup matches 'correctly'. Sir Bobby won the World Cup with England in 1966, of course.
He said: "There's no worries that if they get some of the football in Sheffield it will be handled correctly, absolutely.
"I hope really that we do get the World Cup in 2018, it's our turn.
"We've stepped back and allowed other countries to have it. It's not right, we deserve it more."
Nick Clegg, a Sheffield Hallam MP and the Liberal Democrat Leader has been confirmed as an ambassador for Sheffield 2018.
He said: "Sheffield has such an extraordinary footballing heritage, the place of the oldest club, the oldest professional ground, it would be a bit like bringing football home.
"With the two grounds soon up to FIFA standards I think it will be such a transforming thing for the City, so I'm delighted to be an ambassador."