Wardley started off as a stage manager at Windsor's Theatre Royal then moved on to the film industry, including creating the special effects for five of the James Bond movies. He was later hired by the Tussauds Group due to his experience in designing animated figures and rides for amusement parks. His first project was the creation of the animated show "50 Glorious Years" for Tussauds "Royalty and Empire Exhibition" at Windsor.
He is well known for a dark ride he designed in partnership with Spark's Creative Services for Chessington World of Adventures, which opened in 1990. Professor Burp's Bubbleworks took visitors on a tour of a fizzy pop factory set in Transylvania. Wardley stated that they treated the ride as if it was a comic book and that it was his favorite ride to create. Bubbleworks was closed at the end of 2005 and rethemed.
Wardley also worked with Chris Sawyer and Frontier Developments for RollerCoaster Tycoon 3, a game about amusement park management. His name is also a secret cheat code in the game - when visitor's title is named after him all height restrictions are removed, alluding to the severe height restrictions that his most well-known work at Alton Towers was required to comply with.
On 22 January 2013 John announced his retirement, meaning Flug der Dämonen would be his last attraction. In April 2013 John's autobiography (titled "Creating My Own Nemesis") was published.
Despite this, there is speculation that John Wardley may be working with Alton Towers on a new ride. This increased with the recent formal screening option submitted for at Alton Towers for a ride with "timber truss construction" as John has said he believes a wooden roller coaster should be built at Alton Towers.