Published Monday, 06 July 2009
The comments, made on his Radio 2 show, provoked 61 complaints from listeners who said Ross was being homophobic.
During the broadcast, on May 9, he discussed prizes in a competition themed around the fictional teenage pop star.
He said: "If your son asks for a Hannah Montana MP3 player, you might want to already think about putting him down for adoption before he brings his... um, partner home."
But Ofcom found that the comment was "clearly presented as a joke" and part of Ross's "irreverent, challenging and at times risque humour".
The presenter found himself in hot water last year after he and fellow DJ Russell Brand left obscene messages on actor Andrew Sachs's answerphone, which were also broadcast on Radio 2.
Ross was suspended for 12 weeks by BBC bosses, but walked straight back into controversy on his radio show by joking about having sex with an elderly woman.
His radio show, which has been on air since 1999, features light-hearted exchanges between Ross and the programme's producer Andy Davies.
Ofcom said: "The comment was clearly presented as a joke intended to make light of the reactions that some parents may have if their child chooses a toy that is very widely recognised to be designed and marketed for the opposite sex.
"The humour was therefore based on the absurdity of the scenario and was not intended to cause offence.
"The fact that this comment was intended to be a joke was illustrated further by the reaction from Andy Davies, who was heard laughing.
"Ofcom therefore considered that the nature of the joke and the tone and manner in which it was presented made clear that it was not intended to be hostile or pejorative towards the gay community in general."
The watchdog found that any children listening would have been unlikely to understand the implication being made.
Ross's comments provoked anger from a number of listeners.
After the broadcast, Karen Mills told Pink News: "How can these people earn such huge sums of public money to come out with this discriminatory rubbish?
"What would be the message to a young gay man listening to this? Worse still, how might such comments reinforce and support homophobic bullying in the playground?"