[1][2] Over the centuries, the square has been home to many of Dublin's most prominent people: lawyers, churchmen, politicians, writers and visual artists.

The first Luke Gardiner (died 1755)[4] was a highly successful banker, developer and Member of Parliament for Dublin in the early 18th century.

The major continuous part, much of which he purchased from the Moore family in 1714,[1] was a large piece of land to the East of the then-established city.

An early plan and elevation, known then as Gardiner Square was drawn up in 1787 by Thomas Sherrard, surveyor to the Wide Streets Commissioners.

The original West side plans show a palatial stone-clad street frontage[1][6] with a terrace of brick residential houses behind the cladding.

[1] After completion, contemporaries Warburton, Whitelaw and Walsh said of it: This square, which is now completely finished, is neat, simple and elegant, its situation elevated and healthy … the elevation of the houses, the breadth of the streets, so harmonize together, as to give pleasure to the eye of the spectator, and to add to the neatness, simplicity, and regularity everywhere visible, entitling this square to rank high among the finest in Europe.

The residents' resistance to the attempt to 'provide an additional lung for congested Dublin' were so fierce that The Lancet wrote that despite the park's small size it 'seems sufficient for an Irish battlefield in the holidays.

Half of the south side of the square was bought up by Leinster Estates, a company owned by the property developer Matt Gallagher, in the early 1970s.

Despite high objections from the Irish Georgian Society (IGI), permission for the office block scheme was granted in October 1967.

Despite the formation of Mountjoy Square Estates in an attempt to take up Gallagher's offer, permission was granted for the office scheme again in July 1969.

This led to Mountjoy Square Estates purchasing the plots in December 1969 for £68,000 with the condition that all the houses would be restored individually, and all adhere to the Georgian aesthetic.

After brickwork began to fall into the street, Dublin Corporation demolished many of the houses to first-floor level for safety reasons.

Following his death, the site remained untouched until 1978 when it was purchased by Stephen Treacy, though he failed to progress the project and by 1981 parts of brick cladding from the 1970s construction fell into the street, crushing two cars.

[14] Subsequently, his descendant Desmond Guinness and first wife Mariga, attempted to save and restore the gracious character of the square in 1966–75, buying No.

John O'Leary, a leading Fenian, poet, editor of The Irish People, mentioned in W. B. Yeats' poem September 1913,[15] lived at no.

[17] Dáil Éireann, the parliament of Ireland, having been suppressed by the British authorities as a dangerous organisation in September 1919, met before the foundation of the Irish Free State at the home of the republican Walter L. Cole in Mountjoy Square.

The exception was the twelve men of D company under the command of Captain Seán Heuston who met at Mountjoy Square with the mission of taking the Mendicity Institution across the river from the four courts.

[19][20] Tim Healy resided at 1 Mountjoy Square, having lived previously on the adjacent Great Charles Street in number 50.

[28][29] An infamous brothel, known as The Kasbah Health Studio,[30] frequented by numerous senior Irish businessmen, politicians and churchmen was located in the basement of number 60 Mountjoy Square West[30] from the late 1970s until its closure in the early 1990s.

[30] Irish radio presenter, journalist, former Trinity College SU president and student activist Joe Duffy was born on Mountjoy Square in 1956.

[38] Several scenes from Georgie's Story, the third episode of Mark O'Halloran's award-winning television mini-series Prosperity, screened on RTÉ in 2007, were filmed in and around Mountjoy Square park.

The rock/pop band U2 used to rehearse in a squat on Mountjoy Square in the late 1970s and were photographed by Patrick Brocklebank, published in "The Dublin Music Scene and U2, 1978–81".

On 14 May 2012, a meeting of Dublin City Council formally established Mountjoy Square as an Architectural Conservation Area.

In 2018, the Dublin City Council proposed restoring Mountjoy Square to its 1837 design by re-creating the 4.4-acre park at its centre.

[44] Close to the centre of Dublin city and having the major artery Gardiner Street as its West side, Mountjoy Square has considerable transport links in its immediate locality.

In 2009, the Dublin Bikes bicycle sharing system was launched and has one of its more northerly stations on the west side of Mountjoy Square, providing easy access for commuters, locals, and tourists.

Prior to the installation of public lighting schemes, most houses would have had a cast iron gas lamp holder atop the railings at the bottom of the granite steps.