Gavin leaves the council next month after four years, where work has included handling crisis communications surrounding allegations of abuse by staff towards pupils at the Kerelaw secure unit.
An inquiry into these allegations is ongoing.
Glasgow City Council is now on the hunt for a replacement for the role, which reports to media manager Jim Clark.
Prior to joining Glasgow Gavin worked as a PRO at the Greater London Authority and the London Borough of Brent.
At Pagoda, Gavin will report to Ian Coldwell. Pagoda clients include Edinburgh City Council, which hired the agency earlier this year to handle communications surrounding its housing stock transfer.