Mahon joins on 19 May as communications manager, from her current role as comms and marketing manager at West Dunbartonshire Council.
The 35-year-old replaces retiring public relations manger Hugh Dougherty, who has held the post since the council was set up in 1996.
Mahon said: 'I am looking forward to delivering effective public information, using both traditional and new media, to ensure residents, businesses, the media and communities stay informed about the council and the services it provides.'
Mahon has wide experience of communications and marketing within the private and public sectors, including a stint at Lanarkshire Brand, where she promoted the area.
Dougherty, who is 60 this year, retires at the end of May. He first joined councils in 1985 as education press officer for the former Strathclyde Regional Council.
Last October, East Renfrewshire Council launched a brand identity for a sustainable travel project in the Scottish town of Barrhead. The new brand identity, 'Go Barrhead!', was developed by the council's in-house PR service with design agency Arctic Creative, based in Glasgow.