Cox began his career as a hardcore/rave DJ in the mid-1980s. He has performed at clubs such as The Eclipse, Edge, Shelly's, Sterns Nightclub, Heaven, Sir Henry's in Cork, Ireland and Angels and The Haçienda, as well as raves for Fantazia, Dreamscape, NASA and Amnesia House. He now spearheads two record labels, Intec Records and 23rd Century Records. He also has his own stage every year at Ultra Music Festival, Tomorrowland, and Electric Daisy Carnival called Carl Cox and Friends.
He also ran Ultimate Base at the now defunct Velvet Underground on Charing Cross Road in the mid- to late 1990s. Of his many DJ highlights, he also managed to cram in the Millennium (1999 to 2000) New Year's Eve twice by flying and cheating the timezones. He has had shows on Kiss FM and was a monthly live, global resident for BBC Radio One's Essential Mix in 1998–99, as well as over a decade's worth of Ibiza live mixes broadcast from Club Space. Cox's performances in Ibiza in Residence and Club Space included Kryoman