JSB's CEO Leslie Benson becomes a senior MD in FTI Consulting's Strategic Communications business following the group hire.
His team of 15 will work with the small existing employee engagement and change comms practice in FTI's London office, which is led by MD Lucy Phillips, who will now report to Benson.
It will also work with FTI's global employee engagement teams including one in the US, led by Angie Gorman, and another overseen by Hartmut Vennen in Germany.
JSB and FTI have partnered on various projects over the last 10 years. Recent clients of JSB include Transport for London, Imperial College London, Deloitte and the retailer Primark.
Benson said that the expanded team would work with comms and HR leaders and the C-suite to "drive business results by enabling people to perform to their full potential at work".
Employee engagement was identified as the second biggest priority for global in-house PR pros in a recent study, and Edward Reilly, global CEO of FTI's Strategic Comms segment, said: "Whether in the course of normal business operations or during moments of change, challenge or opportunity, such as mergers, corporate restructurings or crises, senior corporate leaders are increasingly focused on ensuring their employees’ actions are aligned with their business objectives."
FTI's comms operation, which generates about a tenth of the professional services firm's income, had 170 staff in London and 599 globally at the end of 2015, according to the PRWeek Global Agency Business Report.