ČT3 (Česká televize 3, "Trojka") was a Czech public television channel, operated by Czech Television. ČT3 broadcast originally in 1993 when it replaced the previous station OK3. Unlike the other two channels of the Czech Television at the time, ČT1 and ČT2, ČT3 broadcast its program largely in foreign languages and 24 hours a day.
 ČT3 was reestablished in 2020. Its broadcast began on 23 March 2020 during the COVID-19 pandemic and was now intended as a nostalgic channel primarily for seniors. Its program composition was mainly filled with programs from the archive of Czechoslovak and Czech television. It was originally supposed to broadcast only temporarily, but in 2021 it was decided to keep it permanently. In 2022, however, Czech Television announced that, due to the need to limit financial expenses, ČT3 would end broadcasting on 1 January 2023. The ČT3 station broadcast from 5.59 until approximately two in the morning and was available in terrestrial, satellite and cable broadcasts. Return of the channel is currently planned.
 The history of the ČT3 station stems from the third broadcast circuit of the Czechoslovak Television, which was originally used to broadcast Soviet television in Czechoslovakia. In the early 90s this circuit was divided into two new stations as part of federalization. On 14 May 1990, station OK3 began broadcasting for the Czech Republic, and on 6 June 1991, station TA3 for Slovakia. From 1 January 1992, the station OK3 was operated by the newly established Czech Television. After the Dissolution of Czechoslovakia, the OK3 channel was renamed ČT3 on 1 January 1993. Broadcasting of ČT3 was terminated on 31 December 1993.
 From 1 January 1994, Czech Television broadcast the program offer of the ČT2 channel on the ČT3 frequency network. Simultaneous broadcasting of ČT2 ended on 3 February 1994, when this channel left the original frequencies and remained only on the frequencies of the former ČT3 channel. From 4 February 1994, the first Czech full-scale commercial station, TV Nova, began to use the vacated space.
 After 2010, Czech Television began planning a new children's channel, which was officially known as ČT3. It finally started broadcasting on 31 August 2013 under the name ČT: D.
 Establishment of the temporary TV channel ČT3 was announced by Czech Television on 18 March 2020. According to Czech Television (ČT), senior citizens, who were a vulnerable group during the covid-19 pandemic, spent the most time at home during the crisis and public television wanted to provide them with a television program adapted to their needs. Due to the extraordinary situation, ČT stopped producing most of its regular programs and was able to use the funds for the creation of a new channel. Broadcasting of ČT3 started on 23 March 2020 at 9 a.m.
 On 24 March 2021, the Council of Czech Television approved the transition from test broadcasting to regular broadcasting and agreed to its financing until the end of 2021. In November 2021, CEO Petr Dvořák stated that Czech Television is counting on the ČT3 station in the following years as well, however in November 2022, Czech Television announced that its operation would end at the end of 2022 due to the need for financial savings. ČT3 broadcasting ended on 1 January 2023, in the first minutes of the new year, after the New Year's toast.
 Program Director of Czech Television Milan Fridrich stated on 19 July 2023 that ČT3 might be restored in future if financial situation of Czech Television might get better. Elected Director-general Jan Souček who is to assume office in October 2023 confirmed that he supports restoration of ČT3. On 4 September 2023 Souček announced he plans restoration of ČT3 with possible date set for 2024/2025. Channel will most likely change format from a retro channel.