Eyre replaces Will Whitehorn, who had chaired the group for the past seven years.
Eyre told PRWeek: 'The walls between advertising and PR are coming down, particularly in terms of social media, which puts PR companies in an extremely strong position. The market is changing very quickly for brand owners and Next Fifteen's focus on digital growth seems entirely the right strategy.'
Eyre's appointment will be instrumental in moving Next Fifteen further into the digital space, according to Group CEO Tim Dyson.
To further build its digital presence, the group today announced the acquisition of CMG Worldwide Limited, trading as Bourne, a global digital agency based in Glasgow with offices in London and New York.
Next Fifteen has bought 80% of the agency for an initial £1.95m. Bourne has £2.5m of revenue in calendar 2010, with clients including Dell, Ricoh, Lumesse and Symantec.
Dyson said: ‘The PR industry is going through an exciting market transition that is creating significant growth opportunities in digital marketing for Next Fifteen. Richard's knowledge of the broader marketing industry will be invaluable as we go through this transition.’
Eyre added that he expected to take an active role in the strategy of the business. He commented: 'I don’t really do back seat roles. I'm only interested in working with companies that want me playing a material role in the management team planning strategy and delivery.'
He is also currently a director of marcoms M&A specialist Results International as well as firms such as telecommunications firm MGt, accountants Grant Thornton, radio station Atlantic FM and the Advertising Standards Board of Finance.
Formerly he served as CEO of ITV Network, Capital Radio and director of content and strategy for the RTL Group.
The group now has 48 offices in 19 countries and owns agencies including Text100, Bite Communications and Lexis.