An actor by profession, Prashanth Thiagarajan made his debut with the film Vaigasi Poranthachu (1990) at the early age of seventeen. In a career spanning over more than 30 years, Prashanth has appeared in Tamil films, Telugu and Malayalam films. Although he appeared in films such as Vanna Vanna Pookal (1992) and Chembaruthi (1992), he rose to fame with Thiruda Thiruda (1993). His noteworthy films include Tholi Muddhu (1993), Rasa Mangan (1994), Aanazhagan (1995), Krishna (1996), Jeans (1998), Chocolate (2001), Winner (2003), Shock (2004), London (2005) and Ponnar Shankar (2011), which was his last appearance.

In 2016, Prashanth made his comeback in the action comedy Saagasam. The film had an average box office collection. His other acting credits include Johnny (2018) and Vinaya Vidheya Rama (2019).