Gateley is set to be the first British law firm to list in London after it announced its stock market flotation on Tuesday in a move that will give it access to funds for expansion.
The commercial law firm, with six offices in England and one in Dubai, said it would have an initial market value of about 140 million pounds ($218 million) when it floats on London's junior AIM market.
Chief Executive Michael Ward said going public would enable the company to diversify and incentivise partners and staff.
"We can use our balance sheet and shares in the marketplace, and that differentiates ourselves from our competitors," he said in an interview.
The firm could expand into complementary areas such as consultancy in human resources, environmental law and town and country planning, he added.
Slater & Gordon, the first international law firm to go public, with a listing in Australia in 2007, showed the advantages that could be gained from a listing, he said.
Slater & Gordon has grown quickly in Britain through acquisitions in recent years.
Last year after a change in the law, Gateley adopted an "Alternative Business Structure" which allows non-lawyers to own and invest in law firms as a step towards going public.
The firm's 81 partners will be part of the transaction, he said, and they had all signed up to restrictions limiting how quickly they can sell any shares.
Broker Cantor Fitzgerald Europe is running a roadshow to attract investors, he said, with the listing planned for the end of the month.
