Reporting to executive chairman Rosemary Brook, he will join on 10 April after ten years at GCI.
Harries will also claim a seat on the board of Kaizo's parent company The Argyll Consultancies, freeing up CEO Crispin Manners to concentrate on social media and user-generated content.
Manners will remain Argyll's principal shareholder. He stepped back from the day-to-day running of Kaizo in 2004, promoting Liz Andrews and Paul Smith to the roles of joint MD. Andrews and Smith both left in 2005.