After the National Youth Theatre and repertory theatre in Guildford and Hampstead, Potter received his first role in British television at the age of 23 in the television drama The Bonegrinder (1968) written by Dennis Potter.

The Italian director Federico Fellini chose him for the main role of Encolpius in his film Satyricon.

After this star role, Potter's career tended back to smaller roles again: mostly B-films and television productions like the film adaptation of W. Somerset Maugham's Olive.

He also appeared in horror films, including Craze with Jack Palance, and television series such as Doctor Who.

In 1985 he again took a part in a production concerning Ancient Rome: the American mini-series A.D. in which he portrayed the Roman politician and opponent of Nero, Gaius Calpurnius Piso.