Hawes began his television work in factual programming, working in the BBC's documentary and current affairs departments. In parallel, he launched the Young Shakespeare Company, a professional touring theatre company, which he ran as artistic director and which performed in the UK and US.
In 1990, he directed Prince Charles in The Earth in Balance, the prince's documentary about the challenges facing the global environment, which filmed across the world, including locations such as Hong Kong harbour, to Kennedy Space Center and the Sumatran jungles. Other documentary work includes the investigative strand Inside Story for the BBC, the Emmy Award-nominated Egypt's Golden Empire, and the 2003 drama-documentary, Lawrence of Arabia: The Battle for the Arab World, which he both wrote and directed. It used the story of T. E. Lawrence's life as a prism through which to study the shaping of the Middle East in a post-9/11 world.
Hawes moved into drama, earning his spurs on popular drama The Bill. Hawes' work on the BAFTA winning Doctor Who was particularly well received. He directed Christopher Eccleston in "The Empty Child" and "The Doctor Dances" which won the Hugo Award for Best Dramatic Presentation, Short Form in 2006. As a result, Hawes was hired to helm episodes of the second season, directing the Christmas special and introducing David Tennant as the new Doctor. "School Reunion" was also nominated for the 2007 ceremony. Hawes was awarded the BAFTA Cymru Award for Best Drama Director for his work on "The Christmas Invasion".
In early 2006, Hawes directed an Andrew Davies-scripted 90-minute television drama based on the Lady Chatterley's Lover obscenity trial of 1960, The Chatterley Affair. This one-off drama for digital television channel BBC Four features Doctor Who star David Tennant as Richard Hoggart. It was one of the first of what would become an extremely successful run for single dramas on British television, often bringing big screen stars to individual and authored projects. The Chatterley Affair also won Best Single Drama in the same BAFTA awards as the Doctor Who success.
In 2007, he linked up again with Andrew Davies to direct an adaptation of the 18th-century novel Fanny Hill, for Sally Head Productions and BBC Four.
In 2008, Hawes was appointed lead director on the BBC fantasy series Merlin, which began broadcasting in September 2008.