Fitch was previously a board director at the company. He joined the firm, which was acquired by US firm Teneo last year, in 2014. Before this he spent nearly four years as head of comms at insurance market Lloyd's of London.
He has also previously worked for the Department for Work and Pensions and FleishmanHillard Fishburn predecessor Fishburn Hedges, and started his career as a local newspaper journalist.
Blue Rubicon's previous MD Chris Norton left the firm in January to become EMEA comms chief at Facebook – which also has a new global comms head as of last week.
Blue Rubicon CEO Gordon Tempest-Hay said that since 2014, Fitch had "brought vast experience to bear on existing clients, as well as securing significant new clients to grow our strategic communications business".
Fitch said: "I am thrilled to take up the opportunity to drive forward Blue Rubicon’s exciting plans. We are increasingly working to help solve the most complex reputation challenges and have made a name for ourselves tackling large-scale reputation turnarounds.
"As business leaders increasingly demand joined-up services that add value, we can offer a rare mix of the highest quality strategic thinking coupled with the best-in-class reputation campaigning needed to protect and transform corporate reputations."
Blue Rubicon clients include Tesco, Facebook, McDonald’s, Coca-Cola, Mondelez and O2.