Shoosmiths has reached 100 employees at its Manchester office.
The national law firm opened at Spinningfields just over four-years-ago with only six staff, and now runs a full service office.
Associate Will Sanderson is the 100th employee, joining the real estate team.
Partner and head of office Harold Brako, who was among the original Manchester six, said: "We said in our first year here that we were in it for the long-haul. Well, we're still here, and we're flourishing."
Opening in January 2009 offering financial services through its Recoveries Services group, Shoosmiths went full service after just 12 months, and its offering in the city now includes corporate, commercial, real estate, litigation, banking, restructuring, employment, private client and pensions advice.
Brako added: "We bucked the trend when we opened here - just as the economic storm clouds were gathering - but were confident we could offer the sort of legal services the city and the wider region was looking for.
"It was a bold move that has paid off in resounding fashion. Shoosmiths is now an established player here, with high calibre clients operating in a variety of sectors across the North West."
Shoosmiths, which opened an Edinburgh office last year, occupies 15,000sq ft of space across two floors of 3 Hardman Street. It added to its original 10,000 sq ft in 2011 to accommodate growing staff numbers.
Total number of staff in Manchester is now at 105, with five more having joined immediately after Sanderson.