Manchester Central Library beat One St Peter's Square, Manchester City Football Club Academy and Manchester Science Parks' Citylabs to the award from the Greater Manchester Chamber of Commerce.
The winner was revealed at the chamber's property and construction annual dinner yesterday evening.
The chamber's property and construction committee, which consists of 15 professionals from a range of businesses across the sector, invited nominations for the shortlist, and undertook a series of site visits in August and September.
Manchester Central Library reopened in March after a £48m refurbishment by Manchester City Council.
Laing O'Rourke was the contractor on the scheme. The architect was Ryder Architecture, M&E services were provided by NG Bailey, structural engineer was URS, M&E engineer BDP, heritage advisor was HOK and cost consultant was Aecom.
Mike Gibson, chairman of the chamber committee, said: "Manchester Central Library has been selected as this year's building of the year award winner as it is a high quality reconstruction and refurbishment of one of the city's crown jewels. The attention to detail in preserving the historic character of the building is matched by the fine updating of the Library's facilities, making it a superb asset for the inhabitants of a 21st Century city.
"It's also worth noting that the use of Building Information Modeling in the reconstruction process has helped establish Manchester as one of the global leaders in the application of this new technology."
Last year's winner was Number One Riverside in Rochdale, built by the local authority.