The Canal & River Trust, formerly British Waterways, has sold the 10,376 sq ft office building in Manchester's Castlefield to private buyers for £925,000.
Giant's Basin is partly let to Tangerine Public Relations & Coaching which occupies 5,500 sq ft on the ground, second and third floors.
There remains 4,800 sq ft of office space to let on the ground and first floors of the four-storey building.
The building was producing an income of £19,540 a year for the Trust, with the rent due to increase to £39,059 with effect from January 2013.
Jonathan Tinsley, senior estates surveyor for the Canal & River Trust, said: "The sale of this building follows a strategic review of the non-operational property held by the Trust and we expect more sales over the coming months, as we rationalise our investment portfolio to focus on core incoming producing assets. The receipts from the sale will be reinvested."
David Murray, partner at the Manchester office of Sanderson Weatherall advised the trust. He said: "The successful sale of Giant's Basin proves the ongoing demand for such freehold buildings in central Manchester. The inclusion of 20 car parking spaces means the property represents good value in the current market, especially for anyone looking for owner-occupation."