The Office of Public Works (OPW) (Irish: Oifig na nOibreacha Poiblí) (legally the Commissioners of Public Works in Ireland) is a major Irish Government agency, which manages most of the Irish State's property portfolio, including hundreds of owned and rented Government offices and police properties, oversees National Monuments and directly manages some heritage properties, and is the lead State engineering agency, with a special focus on flood risk management.

It lies within the remit of the Minister for Public Expenditure, National Development Plan Delivery and Reform, with functions largely delegated to a Minister of State at the Department of Public Expenditure, National Development Plan Delivery and Reform with special responsibility for the Office.

The OPW has a central role in driving the Government's property asset management reform process, both in respect of its own portfolio and that of the wider public service.

In the 21st century, the OPW includes the Government Publications Office, and publishes the State gazette, Iris Oifigiúil, and also manages some aspects of the household of the president of Ireland.

The body of seven salaried commissioners were made responsible for forts, palaces and other public buildings, including Dublin Castle, specifically covering their furnishing and maintenance.

in 1842, which expanded the OPW's remit around fisheries considerably, and was followed by further related acts over the following five years, which also added a role in the promotion of deep-sea fishing.

[6] The navigation work employed considerable numbers of people during the Great Famine, and over half a million pounds was spent on channel deepening, and the building of piers, embankments and bridges by 1850.

The OPW was additionally given powers under legislation concerning tram and light rail systems, from 1860, 1861 and 1889, and could advance loans towards construction and maintenance costs.

Later in the 19th century, the OPW was further given the power to fund railway construction in congested districts in the western side of Ireland, and it was involved with at least one such project, in County Donegal.

[6] The OPW assumed powers over some heritage properties from 1869, with transfers of historic buildings formerly vested in the Church of Ireland taking place over following years.

These included the remains of major monastic settlements, such as Glendalough, the Rock of Cashel, Clonmacnoise and Monasterboice, as well as later monasteries, abbeys and friaries, some cathedrals, round towers, high crosses and monks' cells; also transferred were some ogham stones.

[6] Eighteen additional properties were assigned to the care of the OPW in 1882, under the Ancient Monuments Protection Act 1882, including stone forts such as the complex of megalithic monuments including Newgrange, Knowth and Dowth, now known as Brú na Bóinne, the Grianan of Aileach and Staigue Fort, the stone circles at Moytura, Cong, County Mayo, the Hill of Tara, Navan Fort, Slieve na Calliagh, and, in County Sligo, Queen Meave's Tomb and the Knocknarea passage tomb.

[11] From the 1980s, the OPW led work on Dublin Castle, the former College of Science on Merrion Street turned Government Buildings, and the Royal Hospital, Kilmainham.

The OPW continued an annual programme of property acquisition by purchase and lease, and disposal, including civil service, police, prison and educational facilities, as well as managing a range of strategic projects.

[16] In 2003, the OPW was assigned the task of locating and contracting, fitting-out or adapting offices for 10,000 civil servants scheduled to move out from Dublin to various other urban areas in a mass decentralisation programme, in addition to which it completed a new Garda Siochana command centre at Harcourt Square, and a passport production facility in Balbriggan.

[17] In 2004–2005, projects included the construction of new staff offices, a restaurant and entrance facilities at Dublin Zoo, and the completion of a multi-year restoration of the Victorian Palm House at the Botanic Gardens and of the glass houses on Garinish Island, as well as supporting both the development of the Aviva Stadium and of the new National Sports Campus at Abbotstown, County Dublin.

[22] The OPW is the main provider of services to departments and agencies of the Irish government related to property procurement, construction and fit-out, and management.

Specific services related to construction and fit-out include design and architecture, valuation and quantity surveying, project management, and engineering.

[28] As of 2019, the OPW oversaw 434 watercourse monitoring stations, with more than half a million visits to the Office's water level data website.

[1] The Commissioners of Public Works published an annual report from 1832 and 1939, halting during The Emergency, as World War II was known in Ireland.

[36] The OPW has historically published a wide range of books and booklets on Ireland's heritage properties, as well as the State's official gazette, Iris Oifigiúil, copies of bills, Acts of the Oireachtas and various other materials.