Wills played in the early days of rock music in Cambridge, from c.1961 in the Vikings, then a succession of local bands: the Sundowners, Soul Committee, Bullet and Cochise before joining Frampton's Camel.
Wills joined the blues-rock band Joker's Wild in 1966, replacing Tony Sainty, until they broke up in 1968. He played bass on Peter Frampton's first three albums before ending parting from Frampton in 1975. He became the bassist with Roxy Music in 1976, before leaving the band and joining The Small Faces in 1977, during their reunion period. He left The Small Faces and appeared on David Gilmour's eponymous album in 1978. The next year, Wills became a member of rock band Foreigner . and remained with them for fourteen years.