McGregor, 28, had been accused of sexual assault and questioned along with Big Brother contestant Kenneth Tong and footballer Filipe Morais in Glasgow last November.
Strathclyde Police launched an investigation after the allegation was made but the Crown Office said today there was "insufficient evidence" to prosecute the three men.
A Crown Office spokeswoman said: "A report was submitted to the procurator fiscal at Glasgow concerning Kenneth Tong, Allan McGregor and Filipe Morais in connection with an alleged sexual assault in Glasgow in November 2009.
"After very careful and detailed consideration of all the facts and circumstances following an extensive police enquiry, Crown Counsel have decided that there is insufficient evidence to satisfy legal requirements to institute a prosecution.
"We have sought to keep the complainer informed throughout the investigation. The Procurator Fiscal has informed her of the decision and has offered her a meeting if she wishes to address any questions she may have."
"The former suspects have been informed that in the circumstances there will be no proceedings," the spokeswoman added.