Mayer Brown Rowe & Maw (MBRM) has won a beauty parade against a host of US firms to advise the Panama government on the Panama Canal expansion programme.
The firm will work on all aspects of procurement for the $5.25bn (£2.67bn) deal, which will be the biggest project of its kind since the canal opened in 1914.
Nick Henchie, a partner in MBRM's international construction and engineering group, said: "We'll be advising on all the procurement contracts for the project, including the locks contract, which is a major part of the development."
MBRM has been appointed to act for the Panama Canal Authority following Panama's referendum on the project in October last year. Projects partner Barry Machlin and construction and engineering partners Henchie and Michael Regan will lead on the deal.
The expansion will allow larger, modern ships to use the canal. New locks on the Pacific and Atlantic oceans need to be built to enhance the capacity of the canal, which will form the largest part of the project. The project, which Henchie described as "high profile", has made headlines with its size and cost.
Henchie added: "Although this is a very large project, for bricks and mortar guys like us it's very familiar for us. It's size and profile do make it very exciting and challenging."