Andrew Marshall joins the financial services specialist as EMEA MD.
He spent 13 years at Fishburn Hedges, co-heading its financial practice and chairing its international affiliate network.
He left the agency in March along with fellow director Andy Berry, who joined HSBC to head media relations in the UK and Europe.
Tom Coombes, Cognito founder and CEO, praised Marshall's 'outstanding track record over two decades' and said he would be instrumental in the agency's international growth. Coombes said: 'We have expanded rapidly in North America and now see strong potential growth in Europe, as well as Asia.'