Shortly after entering law school in 1989, Charles obtained a television role which brought him to the attention of a wider public: that of Julien, a young student who comes to study in Montreal, in a TV show called Chambres en ville (Rooms in Town).He also co-hosted the show The Débrouillards alongside Marie-Soleil Tougas from 1990 to 1997.

Charles was a conductor of the chœurs du nouveau monde (New World Choirs) which included notably Les Petits Chanteurs de Laval and Les Voix Boréales, he went on as conductor of the College Vocal, a youth choir that won international competitions in Indonesia, Malaysia, China, Italy and Germany.

Charles presented his first variety show, Noir et Blanc (Black and White) to more than 400,000 spectators across Quebec and the rest of Canada.

A unique feature of his show is the second half, in which he offers to sing and play on the piano and with his band any known song submitted randomly by the spectators.

On October 16, 2006, he launched his album I Think of You, which sold 109,000 copies in its first week, making Charles the highest selling Canadian artist in a one-week period for the year 2006.

[3] Charles was one of the headliners on Parliament Hill at the 2007 Canada Day celebration there, playing the evening's longest set, to an audience of thousands.

[6] In December 2015, Charles acquired the two Radio-Classique radio stations, CJPX-FM in Montreal and CJSQ-FM in Quebec City, under the banner Groupe Musique Greg, pending approval by the Canadian Radio-television and Telecommunications Commission (CRTC).

In 2019, Charles produced and hosted a series of television programs dedicated to the plight of immigrants who came from war stricken countries called le Vrai Nouveau Monde.

In September 2022, there was mild controversy when a video of Prime Minister Justin Trudeau was circulated on social media signing Bohemian Rhapsody with Charles at the piano, while travelling to London for the funeral of Queen Elizabeth II[9]