The win follows a competitive process that included the incumbent, Edelman, which had been working with the FSCS since it took over from Hanover in September 2014.
As part of the new brief, Hanover will manage stakeholder engagement across parliament and industry, social media strategy and help support and deliver the FSCS's ongoing consumer awareness campaign.
The firm, which is the UK's 29th largest PR agency, has also been tasked with managing the organisation's corporate reputation.
Mark Oakes, FSCS head of communications, said: "They are a truly integrated team, with extensive knowledge and understanding of the issues we currently face and those on the horizon. They really got under the skin of our organisation at pitch and are therefore in a good position to help us further develop our reputation in a proactive way."
The account is understood to be worth well in excess of £10,000 per month.