The alleged incident took place in 2016, after the singer had performed at the Gorgeous nightclub in the midlands city, where he was promoting his solo album at the time.
Reports claim that two fans were invited back to the hotel by Williams and his friend Jamien Nagadhana, where one of them - a 20-year-old - was allegedly raped by Williams. West Midlands police have confirmed that Nagadhana has also been charged with sexual assault.
Williams - who will appear in court next month to answer the charge - denied the allegations via a statement and has been bailed three times since his initial arrest.
JLS first came to prominence on 'The X Factor' in 2008 and went on to have a string of hits including 'Everybody in Love' and 'Beat Again' before splitting in 2013.