RTÉ One is Ireland's oldest and most popular television channel, produced by Irish state broadcaster Radio Telefís Éireann. The station began life in 1961 as Telefís Éireann. RTÉ One carries mostly Irish made programmes, consisting of News, Current Affairs, Lifestyle programming and Drama. RTÉ 1 not only competes with the other Irish TV channels, but also with the UK TV networks and other satellite channels that are widely available across Ireland.

RTÉ One was also the sole Irish TV channel until 1978, when RTÉ Two (now Network 2) was created. Since 1998 RTÉ One competes with TV3, a commercial TV channel mostly owned by Britain's Granada Television and Canada's CanWest Global.

RTÉ One is almost universally available on the VHF and UHF bands in Ireland and is available on the Sky Digital satellite service for Republic of Ireland subscribers only.