Hallam’s arrival follows the quiet exit last month of Mindshare’s head of social, Paul Armstrong, who left the agency after two years.
In his new role, said to not be a direct replacement for Armstrong, Hallam will work with the strategy and planning teams to ensure social is integrated throughout and will provide thought leadership.
He will report to chief strategy officer, Matt Andrews, who said he would be "instrumental in ensuring we continue to deliver progressive media strategies for our clients".
Hallam joins Mindshare from VCCP Partnership, where he has led the social strategy for clients that include O2, More TH>N and Unilever Food Solutions, as well as working within the team responsible for Compare the Market.
Prior to VCCP, Hallam spent three years at Wolfstar, rising to head of innovation and launching Wolfstar Labs.
He has also written the book 'The Social Media Manifesto' (Palgrave Macmillan, Dec 2012).