In 1997, he appeared in the play The Warp, which is the longest play ever performed (over 24 hours).

Campbell also appears in an episode of A Touch of Frost Series 6 “keys to the car” as Mr Renfrew, and was the screenwriter and director of the short subject film No Deposit, No Return in 2004.

His television presenting career began on The Gadget Show (Channel 5) followed by BBC One’s prime time science magazine show Bang Goes the Theory. In April 2014 he presented The Treasure Hunters for BBC One with Ellie Harrison which saw them on the trail of earth’s most prized and valuable treasures both natural and man-made. Supersized Earth (BBC One), a BAFTA-nominated series that examined the scale and pace with which humans have transformed the Earth in a generation.

On 2 January 2015, Campbell appeared on and won Celebrity Mastermind, with filmmaker Werner Herzog as his specialist subject. He appeared in The Dumping Ground episode “Fake It to Make It'” which aired on the CBBC Channel in February 2015.

In July 2015, he presented a two-part series for BBC One called Britain Beneath Your Feet.

In June 2016, Campbell presented a three-part documentary for the BBC called City in the Sky, exploring the world of aviation. He presented this alongside mathematician Hannah Fry who specialises in the mathematics of cities.

In December 2016, he was a contestant on Robot Wars alongside Suzi Perry.

In 2017, his debut book Ad Astra: An Illustrated Guide to Leaving the Planet was published by Simon & Schuster.

In October 2019, he chaired The Sky at Night: Question Time filmed at Warwick University as part of the British Science Festival.