RTL9 is a French-language Luxembourgish television channel shown in Luxembourg, France, Monaco, French Speaking Africa and the French-speaking regions of Switzerland.

On 1 July 1954, CLR (Compagnie Luxembourgeoise de Radiodiffusion) changed their name to CLT (Compagnie Luxembourgeoise de Télédiffusion), to state their new ambition: television. On 20 May 1953, the administrative council of la CLR authorised their president, Robert Tabouis, to sign a contract with the Luxembourg government to run a television channel. They obtained the authority of the Grand Duke to permit a state-run monopoly of the channel.

The achievement of the great works of the Villa Louvigny coincided with the start of the construction of a television antenna at Ginsterberg close to Dudelange, a site which assured good reception, due to its altitude of 430 metres (1,410 ft), and its location only 200 metres (yards) from the French border. The project showed the intention to broadcast eastwards towards France.

On 23 January 1955, the date of her 59th birthday, the Grand Duchess Charlotte I launched Télé-Luxembourg with her husband, Prince Félix, marking the official birth of television in Luxembourg. On screen, a young announcer stated that "Télé-Luxembourg will become a part of your family". The first show consisted of introductions to the channel. At the time no studio had been installed at Villa Louvigny. The shows were directed from the building situated at the foot of the Dudelange Radio Tower. This omni-directional transmitter allowed Télé Luxembourg to be well received at first, with a range of around 150 km (93 mi) around Luxembourg, Ardennes, Lorraine and as far as Reims and Mulhouse. Using a VHF channel of E-07 initially showing programmes at 625 lines, and renamed "canal Luxembourg" in France, the standard was kept at the "Belgium" 819 lines or "819 narrowband" used in Francophone Belgium. It used a narrower bandwidth than Radiodiffusion-Télévision Française (with the result that images appear a little less clear), but have the advantage of being able to cram a greater number of transmitters in the same zone, allowing the channel to be seen by French and Wallonian viewers as well as foreign viewers in Germany, Netherlands, and Dutch-speaking Belgium. They were the first private television channel in Europe. Their mission was to show inter-regional information in French in Luxembourg, Belgium and Lorraine.

Even with the addition of some high-ranking staff from RTF (for which RTF unsuccessfully complained against Tele-Luxembourg), such as Jacques Navadic and Robert Diligent, later of Journal de Télé-Luxembourg, the launch of the channel was hazardous, with few experienced staff, teams consisting of former radio technicians who had moved into television. The productions became more professional and from 1956 to 1957, the CLT built a tower towards the top of Villa Louvigny which became the offices and studios of Télé-Luxembourg. The channel, which was then broadcasting for thirty hours per week, eventually was becoming noticed by the viewing public, and became a part of the audiovisual landscape.

As well as the live programmes, such as L'École Buissonnière, there were reports from around the country and neighbouring Francophone regions on Journal de Télé-Luxembourg, and Télé-Luxembourg delivered key programmes from Paris Productions and foreign films and television series. Little by little, the channel created its identity, and marked its difference from the austerity of the national French and Belgian channels. It was marked out by its sense of levity (gameshows, soaps, and nightly films) and fun (strong presence of French presenters such as Pierre Bellemare and Georges de Caunes and announcers such as Anna-Vera). Advertising was present from the outset, but the presenters themselves delivered the messages live. The popular success was so high that their efforts were recognised by hosting the 7th Eurovision Song Contest in 1962 shown across Europe from the Villa Louvigny. This national event was shown live to every café in the country.

In 1969, the Belgian government moved the frequencies for radio relay to cable. Coditel installed a reception station in the Ardennes at Saint Hubert and broadcast a signal from Télé-Luxembourg via cable from Namur, Brutélé which was distributed to the periphery of Liège and Brussels. From then on, est Belgacom which was then able to sell this on to other television distributors. The development of cable in Belgium, and especially Francophone Belgium, meant that Télé-Luxembourg sat alongside the French channels (TF1, Antenne 2 and FR3). Télé-Luxembourg then drew its main revenue from Belgium.

This family-oriented direction was popular and led Jacques Navadic in the 1970s to become the head of the channel. The programming consisted of films, American serials, gameshows, and chatshows using the same presenters gave Télé-Luxembourg star status in Luxembourg, the East of France and Belgium, reinforced by their move to colour in 1972 : as well as the VHF 819 line transmitter (channel E-07) reconverting to 625 lines SECAM, two new UHF transmitters were launched at the Dudelange Radio Tower, one for channel 21 in SECAM for France, one on channel 27 on PAL for Belgium. Every day, at the start of the channel, the heraldic lion of Luxembourg appeared on the circles symbolising the radio waves and the name Télé-Luxembourg, followed by an image of the Dudelange transmitter, with the voice of Jacques Harvey announcing : "Here is Télé-Luxembourg, channels 7, 21 and 27, Dudelange transmitter, Grand Duchy of Luxembourg.". The game shows soon followed, with Coffre-fort presented by Michèle Etzel, under the slogan Vivement ce soir sur Télé-Luxembourg, and advertising based on car stickers which viewers were encouraged to place in their cars, with these cars then being filmed and broadcast on air.