Tunstall, who was recruited by former PPA chief executive Jonathan Shephard soon after his appointment in April 2008, took over the day-to-day management of the organisation following Shephard's swift exit last month.
Former Haymarket Media Group managing director Eric Verdon-Roe, who has been consulting for the PPA since Shephard's departure, praised Tunstall's contribution.
He said: "I saw Sarah in action in my previous role as Chairman of the PPA Audit Committee. We have also been working together recently, sharing the day-to-day running of the company until a new chief executive is appointed.
"Her greatest achievement was recruiting the team to run the FIPP World Magazine Congress earlier this year and leading them to produce a world-class international event, despite the tough economic background."
Tunstall will leave the PPA at the end of the year to take up her new role as commercial director at the multi-discipline web agency Fresh Egg, which has BBC Dragons' Den star James Caan as its chairman.
The PPA, which has yet to name a new chief executive, is currently conducting a full review of its activities.
