RTÉ Radio is a division and service of Irish public broadcaster Raidió Teilifís Éireann (RTÉ), which broadcasts four analogue channels and five digital channels across Ireland.

Founded in January 1926 as 2RN, was the first broadcaster in the Irish Free State, in 1932 a 60-kw transmitter was set up in Athlone to cover a major event - the 1932 Eucharistic Congress. In 1933 the service became Radio Athlone (Irish Raidió Áth Luain) and in 1938 was renamed as Radio Éireann. In 1966, after launching a television service, it became Raidió Teilifís Éireann, or RTÉ.

Similar to its parent company, RTÉ Radio is a statutory body, overseen by a board appointed by the Government of Ireland, with general management in the hands of a committee of senior managers, currently an interim leadership team, headed by the Director-General. It is regulated by Coimisiún na Meán, and is mostly financed through the radio license fee, while some funds come through advertising.

The first voice broadcast of 2RN, the original radio callsign for what would eventually become RTÉ Radio 1, took place on 14 November 1925 when Seamus Clandillon, the station director, announced on air: "Seo Raidió 2RN, Baile Átha Cliath ag tástáil", Irish for "This is Radio 2RN, Dublin calling" (or "Dublin testing", depending on the source). Regular Irish radio broadcasting began on 1 January 1926. However, people in most of Ireland could not receive 2RN's (1.5 kilowatt) signal at the time. When faced with numerous complaints from Cork regarding the writers' inability to tune in to the signal, Clandillon remarked in The Irish Radio Review, a magazine dedicated to the service, that they did not know how to operate their sets. A second station, 6CK (mostly relaying the transmissions of 2RN), was established in Cork in 1927.

A high power (initially 60 kW) station was established in Athlone, in 1932, to coincide with the staging of the Eucharistic Congress. 2RN, 6CK and Athlone became known as "Radio Athlone" or, in Irish, "Raidió Áth Luain" and were receivable across virtually the entire country. Radio Athlone was officially renamed "Radio Éireann" in 1938.

Radio Éireann had limited programming hours and a conservative programming policy. It was barely tolerated by some Irish listeners, and was often shunned in favour of BBC stations and Radio Luxembourg. This changed when Radio Éireann became free of direct government control in 1960.

Since 1928 the Radio Éireann studios had been housed in the newly rebuilt GPO on O'Connell Street in the centre of Dublin. The new broadcasting authority established in 1960 was primarily concerned with the introduction of television, but they also recognised that the radio service had long outgrown the cramped conditions in the GPO and that a new home was needed. However it was not until June 1969 that construction began on a Radio Centre alongside the existing Television Centre at Donnybrook on the Southside of Dublin. The building work was finished by April 1971 and after a period of fitting-out, the phased move from the GPO started. Live broadcasts from the Radio Centre commenced on 24 September 1973 and by May 1974 almost all programming was now coming from the new building. The old Henry Street studios however continued to be used for continuity announcements up until 8 November 1976 when the radio service finally ended its long tenancy of the GPO.

A pop music channel, RTÉ Radio 2 (renamed RTÉ 2fm in 1988), began broadcasting on 31 May 1979, founded in response to the growth of pirate radio channels.