The lagoon was included in the National Infrastructure Plan announced by chancellor George Osborne in last week's Autumn Statement.
Bruton Knowles has welcomed the Government's decision to allocate the figure and press ahead with the project.
The ambitious scheme includes a six-mile seawall to harness electricity generated by the rising and falling tides. It could be the catalyst for more development in the area as well as creating hundreds of new jobs.
Mike Rees, head of Bruton Knowles' Cardiff office, said: "If the tidal lagoon doesn't put Swansea on the map nothing will. The scheme bodes well not just for Swansea but also the wider principality and is bound to attract further investment as it progresses."
Mr Rees added Swansea's successful SA1 initiative should serve as a template for the scheme.
"Here we have an ambitious development project which has already achieved great results in terms of bringing new jobs and new homes to the area alongside 65,000 sq ft of new office space for business," he said.
"The SA1 initiative has served Swansea well and seems to fit well in to the city centre scene."
The £1 billion masterplan envisages a seawall looping out to sea, off the mouth of the River Tawe, which will make landfall close to Swansea University's new Fabian Way campus.
The seawall will house 16 turbines generating enough renewable power to run 155,000 homes.