Day, who was chief executive of Burson-Marsteller UK before it merged with Cohn & Wolfe, joins the specialist financial and corporate agency as senior managing director of its strategic communications practice.
The veteran industry figure, with nearly two decades of experience in public affairs and political comms, will lead a new cross-disciplinary team focussing on campaigns and issues management.
He will report to FTI’s EMEA vice chair John Waples and will work on major international campaign briefs as part of his role.
FTI has more than 1,000 employees in London and has offices in the US, Brussels and the Far East.
Commenting on his appointment, Waples said: "It is an exciting period of growth for our business. Stephen brings a flair of originality, deep client experience and an understanding of new demands in our industry. We are delighted he has joined as we continue to expand our international footprint."
Day joined the then Burson-Marsteller in 2013 where he built up its public and corporate affairs division in London, leading on a number of the firm’s international clients, including INEOS, Aldi and Addison Lee.
Day, who has been listed in PRWeek’s ‘Power Book’ top ten in public affairs and political comms for the last three years, was made redundant in July following the merger of Burson-Marsteller with Cohn & Wolfe earlier this year.
He was also recognised in the Financial Times’ ‘Outstanding’ list of the top 100 LGBTQ executives in 2017.
Day began his career as an adviser to the Conservative front bench Trade and Industry Team and has also served as an elected local government councillor.
Later in his career, he worked at FleishmanHillard, Weber Shandwick and then Portcullis as managing director of its public affairs practice.
A former senior Burson-Marsteller source who worked with Day told PRWeek: "This is a great coup for FTI. Stephen is an excellent operator and his departure was a great loss to Burson-Marsteller in the summer."