Firhouse (Irish: Teach na Giúise) is an outer suburb of Dublin, in the county of South Dublin, in the south of the traditional County Dublin in Ireland. It developed from a rural village by the River Dodder, with a second settlement, Upper Fir-house, nearby. It is just outside the M50 orbital motorway, and in the postal district of Dublin 24. It is adjacent to Knocklyon (with which it shares a townland), Ballycullen, and Tallaght. In the historic divisions of local administration, Firhouse is in the civil parish of Tallaght and the barony of Uppercross.

Firhouse is located between Knocklyon, Ballycullen, and Tallaght, close to the foothills of the Dublin Mountains. Located in an area that was predominantly rural until the late 20th century, there were previously a number of mills and two hamlets in the area. It is situated on the eastern bank of the River Dodder, which separates it from Tallaght. Towards the east is Templeogue village.

Firhouse is located by Junction 12 on the M50 motorway and is also served by Firhouse Road and Killininny Road. Several Dublin Bus routes reach the area, including the S6, S8, F1, 15, and 65B.

The origin of the place name derives from the Irish-language phrase 'Teach na Giúise', sometimes translated as 'house of fir'. This name is reputed to derive from what was previously a wild forest of fir trees located in the area. It may also come from a manor that was located at the top of the laneway now joining Scoil Treasa and Scoil Carmel, which belonged to a family called Fieragh with connections to Norway. Like much of the rest of the area, this laneway, which led up to the main house, was lined with fir trees.^{[citation needed]}

According to the Placenames Database of Ireland, the Irish place-name is 'Teach na Giúise'. Among the local population, the pronunciation of Firhouse varies with some using "Fir" and some "Fur", while some historical maps, which tended to capture phonetic spellings of "Furhouse", suggesting an earlier form.

Firhouse was historically the site of a small rural settlement near the river bank, and another, Upper Firhouse, nearby. Firhouse lay within the townland of Knocklyon and was owned, over time, by Walter de Ridelford, and later families including the Burnells, the Bathes, the Nugents and the Talbots, eventually being sold by the Duke of Wharton to the famous Speaker Conolly.

Dated to at least the early 13th century, a weir was built in the Dodder between Firhouse and Balrothery, the district on the north bank opposite, and much of the Dodder's water was diverted to the course of the River Poddle, to supply the then-small Dublin city. The weir is known variously as Balrothery Weir, Firhouse Weir or City Weir, and was the starting point of the canal known as the City Watercourse.

In The History and Antiquities of Tallaght, County Dublin (published in the mid 19th century), George Domville Handcock refers to Firhouse as "a small dirty village, principally inhabited by stonebreakers".