Alex made an appearance in The Ghost and the Darkness (1996) before various TV roles, including EastEnders from 2000 to 2002. He cites a scene where, as Morgan, he had to push Little Mo's face into a Christmas dinner as his most stressful filming experience.
In 2003, Ferns played Career Officer Gordon in the highly-acclaimed trilingual film Joyeux Noël (in English Merry Christmas), which was nominated for Best Foreign Language Film at the Oscars, Golden Globe Awards and the BAFTAs
His theatrical work includes the role of the "tapeworm" (a hallucination) in I.D., a play about Dimitri Tsafendas and his assassination of South African Prime Minister Hendrik Verwoerd, and the 2008 national tour of Agatha Christie's murder mystery And Then There Were None.
Ferns is a buddhist.