A competition for the design of the building was won by architect William Henry Lynn in 1883 and it was built by H & J Martin builders. Designed to reflect the ambitions of the growing city of Belfast, its architecture is a fine example of a public building at the height of the Victorian age. On a black granite base, the Dumfries red sandstone exterior with a slightly Italianate feel, houses a three-floor interior with a sweeping staircase, a pillared foyer, and a fine domed first-floor reading room. The top floor originally included a museum and art gallery. The building is a notable part of the 19th-century cityscape of modern Belfast. It survived undamaged through the Belfast Blitz of World War II and the Troubles of the late 20th century.
The library is in the library and Cathedral Quarter, on the edge of Belfast City Centre and close to the Belfast Campus of the University of Ulster. Two additional buildings were added to the site in the 1960s and 1980s, providing staff accommodation and extra storage. These reflect the growth in the book stock of the library in the intervening decades. A newspaper library is in the 1980s building and accessed from Library Street.
The Library is now run by Northern Ireland Libraries, a public authority covering the whole of Northern Ireland. Belfast Central Library houses a range of sections, including a lending library & Information and Business library still based in the original reading room. A Belfast, Ulster and Irish Department & Music Library on the top floor. It is a major provider of IT facilities on the ground floor providing free internet access.