2JJ commenced broadcasting at 11:00 am, Sunday 19 January 1975, at 1540 kHz (call sign 1539kHz in 1978) on the AM band. The new Australian Broadcasting Corporation (ABC) station was given the official call-sign 2JJ, but soon became commonly known as Double J. The station was restricted largely to the greater Sydney region, and its local reception was hampered by inadequate transmitter facilities. However, its frequency was a clear channel nationally, so it was easily heard at night throughout south-eastern Australia. After midnight the station would often use ABC networks – during their off air time slot – to increase its broadcasting range.
Its first broadcast demonstrated a determination to distinguish itself from other Australian radio stations. The first on-air presenter, DJ Holger Brockmann, notably used his own name (a deliberate reference to his former work for top-rated Sydney pop station 2SM). Owing to 2SM's restrictive policies at the time, Brockmann, whose real name was considered "too foreign-sounding", had been forced to work using the pseudonym "Bill Drake" in prior positions. After an introductory audio collage that featured sounds from the countdown and launch of Apollo 11, Brockmann launched the station's first-ever broadcast with the words, "Wow, and we're away!", and then cued The Skyhooks' You Just Like Me 'Cos I'm Good in Bed.
The choice of a Skyhooks song to introduce the station was significant, as it represented several important features of the Double Jay brand at the time. Choosing an Australian band reflected Double J's commitment to Australian content at a time when American acts dominated commercial pop stations. Most notably, the song was one of several tracks from the Skyhooks' album that had been banned from airplay on commercial radio by the industry's peak body.
Because Double J was a government-funded station operating under the umbrella of the ABC, it was not bound by commercial-radio censorship codes, and was not answerable to advertisers or the station owners. In contrast, their Sydney rival, 2SM, was owned by a holding company controlled by the Catholic Archdiocese of Sydney, resulting in the ban or editing of numerous songs.
2JJ was a product of the progressive media policies of the Whitlam Government of 1972-75, and combined influences from several earlier ABC programs, such as "Room to Move", as well as the freewheeling programming policies of British pirate radio and BBC Radio 1, which was created to target the pirate radio audience. The inspiration gained from the UK led to Double J adopting the tradition of weekly, live-in-the-studio performances by pop and rock bands. Gough Whitlam was unable to also fulfill his aspiration for the establishment of a "National Youth Radio Network", as he was controversially sacked.