Launched on March 26, 1970, it was the first commercial television channel in Thailand.
Channel 3 was officially launched 26 March 1970 at 10:00 Bangkok Time by Prime Minister of Thailand Thanom Kittikachorn. This broadcast area was only limited to the Bangkok Metropolitan Area during its early years. On 1 January 1985, it launched its first Teletext service known as Infonet. On 1 January 1987, it started to air in stereo and, during the 1990s, its stereo broadcast was introduced into its VHF free-to-air station nationwide. TV3 was also experimenting with bilingual transmission using a second audio track in the 1990s.
During its early years, Channel 3's airtime lasted 6-hours, broadcasting from 16:00 to 22:00, and later expanded to midday hours and mornings. For a short period, it started broadcasting 24 hours a day in 1997 but stopped due to the 1997 Asian financial crisis. The network could only resume its 24-hour airtime again on 1 January 2005.
On 1 January 2001, Channel 3 was the first station in Thailand to broadcast a 3D film. The movie, Jaws 3, required the viewers to have a pair of anaglyph glasses that can either be bought from certain stores partnered with the network for the event or attained from elsewhere.