IP firm Mathys & Squire is the first legal tenant of the Shard, the tallest building in Western Europe.
The firm has signed a 15-year lease for 28,500 sq ft on the fifteenth floor of the iconic building, joining other business tenants including broadcaster Al Jazeera, venture capital group Foresight and hospital group HCA.
Partner Paul Cozens said the firm would sub-let a portion of the floor until the firm had expanded to fill the whole space.
Mathys & Squire moved in on Monday (17 March) and currently has 114 members of staff in the Shard.
The firm also has smaller offices in Cambridge, Manchester, York, and Reading. Last year it turned over £23m, and employs a total of 132 staff, patent and trademark attorneys.