Roberts resigned from the Publicis Groupe agency last August after comments he made in an interview with Business Insider about gender diversity provoked a storm of criticism.
In the new role, he will coach Beattie’s senior team and help grow Beattie and its suite of boutique marketing offerings, Only, internationally.
Laurna Woods, chief executive of Beattie Group, said: "We are delighted to have recruited one of the world’s most inspirational business minds to help us expand in the UK, North America and Australasia."
In the interview last July, Roberts claimed that the gender diversity in advertising debate was "over", and that if there was a shortage of women in senior leadership roles, it was because women did not have the same kind of ambition as men.
The following day, his comments were disowned by Publicis Groupe chief executive Maurice Lévy, and he was placed on leave, with a statement from the Groupe calling his views "unacceptable". He resigned four days later.
Beattie pointed out that seven members of its ten-person leadership team were women.
Roberts said: "Beattie is a creative communications consultancy with enormous potential to grow internationally.
"We are an integrated marketing and communications company with foundations in PR, marketing, creativity, content, technology and data. We have no plans to become a traditional advertising agency."