He has acted in Kannada, Tamil, Malayalam, Telugu and Hindi films. His original name 'Prakash Rai' in Kannada screen was rechristened to 'Prakash Raj' by K. Balachander for Prakash Rai's debut movie 'Duet'.

Prakash Raj began his acting career with Kannada Doordarshan serials like Bisilu Kudure and Guddada Bhootha. He later took up small supporting roles in kannada films like Raamachari, Nishkarsha, Lockup Death and etc and was noticed for his dialogue delivery and histrionics. His breakthrough role came in form of Harakeya Kuri starring Vishnuvardhan and Geetha, directed by K S L Swamy. His performance in the movie was noticed by Geetha and she in turn introduced him to her mentor, the noted director K. Balachander. Prakash Rai re-entered Kannada films with a bang through Nagamandala in 1997, directed by T.S. Nagabharana which was selected for Indian Panorama in the International Film Festival 1997.

Prakash Rai is a very famous actor in South India for a wide variety of roles he has performed, most notably as a villain and of late, as a character artiste, in Tamil and Telugu. He is considered to be one of the most natural actors in the film industry, and has a good reputation for his acting skills. He is also the highest paid villain in Indian cinema. He was also a part of Mani Ratnam's stage show, Netru, Indru, Naalai. In 1997, he acted in Mani Ratnam's Iruvar, alongside Superstar Mohanlal. The movie was about the relationship between politicians M.G. Ramachandran and M. Karunanidhi, which he won the best supporting actor award alongside Mohanlal, who won the best actor award.

One of Prakash Rai's greatest hits was his role of Villain in telugu film Okkadu, where he plays the role of factionist, a gangster who is in love with Bhoomika Chawla. After Okkadu, Prakash Raj was flooded with offers. The film was remade in Tamil as Ghilli. The same movie got remade in Kannada as Ajay starring Puneet Rajkumar. The versatile actor then co-starred with major stars and also acted in movies with newcomers. His 2007 production Mozhi, where he played an important role, was a box office hit and praised by critics proving that he can play a comedy role just as good as playing a negative character. Prakash Raj has already had four releases this year, all in which he plays a prominent role. He is acting in more than half a dozen films at the moment including his own production, Abhiyum Naanum.

His production venture in Tamil Mozhi, directed by Radhamohan, starring himself, Jyothika, Prithviraj and Swarnamalya was a blockbuster. He recently acted as a rich businessman in Venkat Prabhu's second film Saroja, a box-office hit. His latest movie is Abiyum Naanum. He is presently shooting for a Telugu film in Hyderabad called Kotha Bandham - Meeru Naaku Ardham Kaaru, in which he plays an IAS officer.Unfortunately, he has been banned from Telugu Film industry due to the troubles he caused in filmmaking. He is concerned about his productions in Tamil and unable to manage all the fields.

 Awards

National Film Awards

• 2008 - Best Actor for the Tamil movie Kanchivaram.". NDTV
• 2003 - Special Jury Mention for exemplary performance. "The Special Jury award (instituted for the first time it is said) goes to Prakash Raj for doing a commendable job in the 12 films (in Tamil, Telugu and Kannada) he had worked in, in the past one year".
• 1998 - Best Supporting Actor for the Tamil Movie Iruvar.

 Producer

Recently he took on the mantle of producer and has produced several movies in Tamil (Kollywood). Most of the movies he produced are box-office hits and also are critically acclaimed.^{[citation needed]} His movies are generally acclaimed by the audience as good quality movies and are also considered as family entertainers. He produced the movie Dhaya in which he acted as the hero with actress Meena which was a hit and earned him a special jury award (a prestigious national award) for his performance. Also as a producer his selection of movies typically have natural storylines. His movie Poi (lie in English) which is directed by his mentor, veteran director K. Balachander, was a non grosser. It has Uday Kiran as the hero. Both the director (K. Balachander) and producer (Prakash Raj) acted in this movie as Good and Bad.

Now he is also very busy as a producer for his 3 forthcoming films. Prakash Raj had danced in a whole song for his film Vellithirai, a folk song named "Kanchi Paanaiyin Maela."

 Director

Prakash Raj has directed 'Naanu Nanna Kanasu' in Kannada (2010). This is the remake of his own production 'Abhiyum Naanum' .

Interview

A recent interview to a Tamil Satellite Channel he said he is Agnostic. He dubs for his characters in various languages he plays. He is well versed in Kannada, Tulu, English, Tamil, Malayalam, and Telugu. He considers K. Balachander as his guru and mentor.