The 40-year-old, who will start work at St James Park on October 1, joins from Warwickshire County Cricket Club having previously held a similar role with Somerset.
"I'm delighted to be given the opportunity to take up the role of Chief Executive at Exeter City," he told the club's official website.
"I'm genuinely excited to be able to work with the Supporters' Trust, board and all the staff to continue to build on the fantastic supporter and commercial support the Grecians currently enjoy and to continue providing exciting football for all to watch."
The role of acting CEO has been held by vice chairman Julian Tagg since 2011 when Norrie Stewart departed the club and Tagg's new role will see him return to focusing on the footballing aspects of the Grecians' set-up.
Tagg added: "Guy's introduction will bring vast experience and drive which will allow him singular focus on commercial, sales, marketing, operations, and communications meaning I can return my focus to my first loves at Exeter City - the youth academy , football in the community and football, where there is much to be done."