The WPP-owned financial, corporate and public affairs specialists arrived in the Adelphi Building last week. The agency was previously situated next to Moorgate station.
The Adelphi Building is described by design and property publication The Spaces as a 1938 structure in the Art Deco style, and "one of central London’s largest office spaces".
Finsbury is occupying the top storey of the 13-floor building. Neighbours include Spotify, publisher Condé Nast, The Economist, Japanese beauty group Shiseido and accountancy body ACCA.
An agency spokesman said: "Our new offices are a significant improvement on the old. We have increased space, improved the working environment, and being equidistant to the city, mayfair and Westminster is a good reflection of a lot of our business."
Finsbury's revenues were flat year-on-year in 2016, according to PRWeek's Global Agency Business Report, with political uncertainty causing clients to press pause on some projects.
The firm announced several promotions on Twitter last week, including new MDs Anjali Unnikrishnan in London and Will Edgar in New York.
Congratulations to all those across the global team who have received promotions pic.twitter.com/Wkcyzw2UEz— Finsbury (@FinsburyGlobal) October 3, 2017