Preston-based AG Built Environment Consultancy recorded £4.1m turnover last year, representing a 25.5 per cent increase.
The results are the best in the company's more than 15-year history.
AG also increased its headcount to 46, across its three offices, including Manchester and Liverpool.
During the year, AG ranked in the top 150 of Building Magazine's annual influential consultants' league table.
Jonathan Shaw, AG's chief executive officer, said: "Our team works incredibly hard, and the increase in turnover represents the fantastic work they deliver for clients across the UK. The growth we've achieved is directly attributed to our people. Without them, we simply wouldn't be where we are."
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