FFW beat rival FCO panel firms during a competitive tender process. It is the firm's fourth mandate for the FCO, which keeps its panel of advisers on its toes with frequent beauty parades.
Technology head Michael Chissick, lead partner for FFW on the deal, said: "The FCO is a longstanding client of ours, but they make everyone compete every time."
The FCO has entered into a five-year deal with IT company LogicaCMG to redevelop, manage and host the FCO's presence on the web. The contract covers the FCO's main UK website as well as the its 200 other websites worldwide.
Chissick said the deal was essential to ensure that the FCO maintains its website presence despite periods of heavy traffic from UK citizens abroad.