Top-100 firms Shakespeares and SGH Martineau have confirmed that they will merge on June 15.
The announcement comes just over two months after the firms revealed they were in talks over a possible deal.
The new firm, with a headcount of 900 people and a combined annual turnover of £75m, will be called Shakespeare Martineau.
It will have offices in several locations around the UK, including Birmingham, Leicester, London and Nottingham as well as one international office in Brussels.
Andy Raynor (pictured) will run the new firm, after being appointed as chief executive at Shakespeares in January. Raynor said: ‘I’m delighted the way this has gone – all our people have worked together brilliantly.
‘Shakespeare Martineau will have a strong commercial personality and the merger demonstrates the commitment of both firms to grow and keep ahead of a rapidly changing and vibrant marketplace.’
Emma Shipp, managing partner at SGH Martineau, said the plans cement the companies’ shared vision ‘to be a progressive and distinctive’ law firm.