TV3 started its trial broadcasts on 10 September 1983 (the day before the National Day of Catalonia), but its regular broadcasts started a few months later, on 16 January 1984. TV3 was the first television channel to broadcast only in Catalan. In 1985, TV3 expanded its coverage to Andorra, Northern Catalonia, the Balearic Islands and the Valencian Community, also Catalan-speaking territories. Since 1985, Montse Armengou Martín has co-directed award-winning documentary films. One year later, TV3 inaugurated its new headquarters in Sant Joan Despí, near Barcelona.
Since 1987, TV3 has broadcast a second audio channel on almost all foreign-language series and movies with the original program audio, first using the Zweikanalton system and currently using NICAM. Local series and movies are usually broadcast in NICAM stereo, although sometimes an audio narration track for blind and visually impaired viewers is provided instead. On other occasions, an Aranese language track is provided.
In 1988, TV3 started a decentralization process, first broadcasting programs in the Aranese dialect of Occitan for the Aran Valley and, one year later, opening branch offices in Tarragona, Girona and Lleida and creating the Telenotícies Comarques, a regional news program broadcast simultaneously in five different editions, one for each of the four Catalan provinces and a fifth one for Aran, the former four being united into one national broadcast in 2017.
A commercial agreement with Italian media firm Fininvest was signed on 25 May 1988, valid until 1991. The agreement gave TV3 exclusive rights to distribute Dallas in Spain, the airing of 20 movies per year, and led to the production of a TV3 variety show hosted by Raffaella Carrà produced by local production house Videotime. Silvio Berlusconi, chairman of Fininvest and an advocate for the development of private television networks in Spain and across Europe at the time, noted that the agreement with TV3 did not change his position on this. Moreover, with the potential rise of private television in Spain, TV3 saw the need to reposition itself and begin exporting its technical and production output abroad through this deal.