The Queen's University of Belfast, commonly known as Queen's University Belfast (Irish: Ollscoil na Banríona; abbreviated Queen's or QUB), is a public research university in Belfast, Northern Ireland, United Kingdom. The university received its charter in 1845 as part of the Queen's University of Ireland and opened four years later, together with University of Galway (as Queen's College, Galway) and University College Cork (as Queen's College, Cork).

Queen's offers approximately 300 academic degree programmes at various levels. The current president and vice-chancellor is Ian Greer. The annual income of the institution for 2023–24 was £474.2 million, of which £105.2 million was from research grants and contracts, with an expenditure of £345.9 million.

Queen's is a member of the Russell Group of research-intensive universities, the Association of Commonwealth Universities, the European University Association, Universities UK and Universities Ireland. The university is associated with two Nobel laureates and one Turing Award laureate.

Queen's University Belfast has roots in the Belfast Academical Institution, which was founded in 1810 and which remains as the Royal Belfast Academical Institution. The present university was first chartered as "Queen's College, Belfast" when it was associated with the simultaneously founded Queen's College, Cork, and Queen's College, Galway on 30 December 1845 as part of the Queen's University of Ireland – founded to encourage higher education for Catholics and Presbyterians, as a counterpart to Trinity College, Dublin, then an almost exclusively Anglican institution. Queen's College, Belfast, opened in 1849. Its main building, the Lanyon Building, was designed by the English-born architect, Sir Charles Lanyon. At its opening, it had 23 professors and 195 students. Some early students at Queen's University Belfast took University of London examinations.

The Irish Universities Act 1908 dissolved the Royal University of Ireland, which had replaced the Queen's University of Ireland in 1879, and created two separate universities: the current National University of Ireland and Queen's University of Belfast.

The university was one of only eight United Kingdom universities to hold a parliamentary seat in the House of Commons at Westminster until such representation was abolished in 1950. The university was also represented in the Parliament of Northern Ireland from 1920 to 1968, when graduates elected four members.

On 20 June 2006, the university announced a £259 million investment programme focusing on facilities, recruitment and research. One of the outcomes of this investment has been a new university library; the McClay library was designed by Boston-based architects Shepley Bulfinch, working in association with Belfast architects, Robinson Patterson Partnership, and opened in July 2009. The building has been named in honour of Sir Allen McClay, a major benefactor of Queen's University and of the Library.

In June 2010, the university announced the launch of a £7.5 million Ansin international research hub with Seagate Technology.