Donegall Square is a square in the centre of Belfast, County Antrim, Northern Ireland. In the centre is Belfast City Hall, the headquarters of Belfast City Council. Each side of the square is named according to its geographical location, i.e. Donegall Square North, South, East and West. It is named after the Donegall family. Other streets to bear their name in Belfast are Donegall Road, Donegall Pass and Donegall Street. Donegall Place, the city's main shopping street, runs from the north side of the square.

On the square are many banks or society branches, including HSBC, Nationwide, Irish Nationwide, Santander, Bank of Scotland, Halifax, Co-operative Bank, First Trust Bank, Bank of Ireland, Danske Bank and Ulster Bank. Many of the above have their Northern Ireland headquarters on the square. The Northern Bank robbery occurred at the bank's headquarters on Donegall Square West. In addition, it is the home to many leading Law Firms including; Millar McCall & Wylie, Sullivans, Rice & Company, McGriggors LLP, and Ferguson Solicitors.

Notable buildings on the square include the Linen Hall Library and the Scottish Provident Building, now a five-star serviced office business centre. The Ten Square Hotel on Donegall Square South was originally a Victorian linen warehouse. Its exterior features carved portholes, with the faces of George Washington, Sir Isaac Newton, Michelangelo and William Shakespeare protruding.

In the Northern Bank robbery cash was stolen from the headquarters of Northern Bank on Donegall Square West in Belfast, Northern Ireland. On 20 December 2004, having taken members of the families of two bank officials hostage to ensure their co-operation, an armed gang seized a total of £26.5 million mostly in unused pound sterling banknotes. This was one of the largest bank robberies in the history of the United Kingdom.

The Police Service of Northern Ireland (PSNI), the Independent Monitoring Commission, the British government and the Taoiseach (prime minister of the Republic of Ireland) all claimed the Provisional Irish Republican Army (IRA) was responsible. This was denied by the IRA and by Sinn Féin. In 2005, the police forces in Northern Ireland and the Republic of Ireland made arrests and carried out house searches. A sum of £2.3 million was impounded at the house of a financial adviser, Ted Cunningham, in County Cork and Phil Flynn was forced to resign as chairman of the Bank of Scotland (Ireland), because he was a director of one of Cunningham's companies. Cunningham was convicted in 2009 of money laundering, had his conviction quashed in 2012 and was convicted at retrial in 2014. Chris Ward, one of the bank officials threatened by the gang, was himself arrested in November 2005 and charged with robbery. The prosecution then offered no evidence at trial and he was released.

The robbery adversely affected the Northern Ireland peace process. It caused hardening of the relationship between the Taoiseach Bertie Ahern and the Sinn Féin representatives Gerry Adams and Martin McGuinness. Although Cunningham and several others were eventually convicted of crimes uncovered during the investigation, nobody has ever been held directly responsible for the robbery. The police investigation is still open and the case remains unsolved.