The advertising watchdog has banned "misleading claims" from the University of East Anglia in Norwich that it is in the top five in the country for student satisfaction.
The UEA is one of six universities to have been pulled up by the Advertising Standards Authority, with Leicester, Strathclyde, Falmouth, Teeside and the University of West London also having complaints upheld against them.
All the universities involved have been told to remove unsubstantiated boasts from their websites and warned they must hold relevant data to back up their ads in the future.
ASA Chief Executive Guy Parker says universities have a responsibility to ensure students aren't tricked into making the wrong choice.
"If you're making claims about your national or global ranking, student satisfaction or graduate prospects, make sure you practice what you teach: play by the advertising rules, in particular by backing up your claims with good evidence," Mr Parker said.
"Going to university involves a big financial commitment and misleading would-be students is not only unfair, it can also lead them to make choices that aren't right for them.
A spokesman for Universities UK said there needs to be better advice so universities know what they can and can't say: "Universities take their responsibilities to use data appropriately in advertising and marketing extremely seriously.
"With a proliferation of university rankings, data and awards now in existence, there is a need for clearer guidelines for universities in how they use this in a way which is clearly understood by students."