DLA and US giant Piper Rudnick Gray Cary agreed to merge in December, creating a global firm with a $1.4bn (750m) turnover.
The merger received unanimous support from the firms partners on both sides of the Atlantic. It required the support of 85 per cent of DLAs equity partners 115 in total to proceed.
The merger has catapulted DLA into the global top 10, with 2,700 lawyers and a turnover expected to reach $1.4bn next year. Managing partner Nigel Knowles will serve as joint chief executive officer alongside Piper Rudnicks co-chairs Frank Burch and Lee Miller.
Following the October merger between Piper Rudnick and California technology expert Gray Cary, the new firm operates as DLA Piper Rudnick Gray Cary.