Paul Nicholls, Dibb Lupton Alsop's North West managing partner, is to take the reigns at its 250-lawyer London office.
The London office has lost several partners and assistants to rivals this year, the latest being head of IT and telecoms David Barrett, who moved to US firm Arnold & Porter.
Nicholls has a reputation as a troubleshooter, having transformed Dibbs' struggling Manchester office into one of the city's leading practices.
Dibbs senior partner Roger Lane-Smith described Nicholls as a "very good leader who inspires people and gets things done".
He said that Nicholls' first priority would be to consolidate the firm's four separate offices in London under one roof, although it will its Lloyd's office separate.
He denied reports that friction existed between the senior partners in the London office.
Nicholls moved from Dibbs' London office to Manchester in 1994 and when Dibbs merged with Alsop Wilkinson two years later, Nicholls was responsible for bedding down the merged offices in Manchester and Liverpool.
Head of property Roy Beckett will take over from Nicholls as managing partner in Manchester.
Nicholls will take up the position from 1 January.