Premgi is the son of veteran director and musician Gangai Amaran and the younger brother of film director and actor Venkat Prabhu. Film composer Ilaiyaraaja is his uncle, while Yuvan Shankar Raja, Karthik Raja and Bhavatharini are his cousins. Premgi started his career as an assistant to film music composer and his cousin Yuvan Shankar Raja, turning a playback singer, singing mostly the rap portions in Yuvan Shankar Raja's compositions, before working with other music composers as well. Working with Yuvan Shankar Raja, he also remixed some of his compositions for the soundtrack albums, the first being "Loosu Penne" from the film Vallavan. In 2006, however, he made his acting debut in Silambarasan's Vallavan as the heroine's friend, following which he starred in his brother, Venkat Prabhu's directorial debut Chennai 600028. The movie went on to become the year's biggest summer blockbuster, establishing Premgi as a comedy actor. In 2005, he became an independent music director with Gnabagam Varuthe starring his brother. After that he composed for Agathiyan's Nenjathai Killathe and for Thozha, in which he played one of the leading roles as well. Apart from film music, he composed music for an episode titled Planet Galatta II – Adra Sakkae in a Singapore satellite channel. He diversified his role as Film actor, composer, music director, singer.