Prithviraj began his career in Malayalam cinema in 2002. The Hindu commented in 2007 that Prithviraj would remain one of the young stars in the reckoning irrespective of the box office prospects of his films.

 Malayalam cinema

In 2002, Prithviraj was cast by Renjith in his second directorial venture, Nandanam. After this he appeared in films directed by Lohithadas, Vinayan, Kamal and Bhadran.

He later went on to do Stop Violence and Swapnakoodu. Shyamaprasad, who cast him in lead role in his film Akale, said that Prithviraj\'s advantages are his talent and intelligence irrespective of his box office successes.

In 2006, he played the role of Sub Inspector Solomon Joseph in the critically acclaimed Vargam. After Vargam, Prithviraj acted in Vaasthavam with the same director, M. Padmakumar, for which he received the Kerala State Award for Best Actor for 2006, and became the youngest actor to win the award. The same year he starred in Lal Jose\'s Classmates which went onto become an all time blockbuster thus increasing his market value and brought about confidence in producers to make more youth oriented movies.

In 2007, he starred in Chocolate, directed by Shafi which was a huge success.In 2008, he starred in Thalappavu (directed by Madhupal) and Thirakkatha (directed by Renjith), in which he took up roles which serve as pivotal characters. One of the reviews of Thalappavu describes it as a film which is truly the coming-of-age film for Prithviraj the actor and that there is a spartan dignity that he brings into his commanding portrayal of Naxalite Joseph. The Sify review of Thirakkatha describes it as a \"genuine attempt that keeps the viewer engaged until the end\". Both Thalappavu and Thirakkatha shared the award for the best film in the Film Critics Award for 2008. He has also made a special appearance in Anjali Menon\'s Manjadikkuru.

In 2009, the success of Prithviraj\'s Puthiya Mukham (directed by Diphan) led the Print & Visual Media to anoint him as Superstar. His other releases in 2009 were Robinhood (directed by Joshy) and Malayalam\'s first Anthology film Kerala Cafe.

In 2010, Prithviraj\'s first release was the offbeat film Punyam Aham followed by Thanthonni and Pokkiri Raja alongside Mammootty.

 Tamil cinema

Prithviraj made his Tamil debut through Kana Kandaen in 2005 as the suave and sophisticated villain.

Soon he got the opportunity to act under the direction of Bhagyaraj in the film Parijatham. Bhagyaraj said in an interview, \"The entire media unanimously appreciated Prithviraj in Kana Kandaen, so it was with that confidence that I signed him\".

Prithviraj\'s Mozhi in 2007 was a critical and commercial success. He also starred in Satham Podathey and Kannamoochi Yenada in the same year.

In 2008, Prithviraj starred in Vellithirai, the Tamil remake of Udayananu Tharam. Rediff described his performance: “Prithviraj makes the best of his assets - his expressive eyes, which glint in fury, soften with love, or brim over with frustrated tears”. The Tamil remake of Classmates, called Ninaithale Inikkum, was his last release. He is currently working in the Tamil and Telugu versions of Mani Ratnam\'s Hindi-Tamil-Telugu trilingual film, Raavana, along with Vikram and Aishwarya Rai. The films are scheduled for a mid-2010 release.

 Telugu cinema

Prithviraj\'s presence in Telugu is through Sivapuram, the Telugu dubbing of the Malayalam hit Ananthabhadram. His first Telugu film was supposed to be Kalakanidhi, directed by Bhushan Kalyan produced by Ravi and Mahesh Kumar under the banner of Swan Creations, but the project got shelved after the death of actor Raghuvaran. Therefore, Prithviraj\'s first straight Telugu release became Police Police (a Tamil - Telugu bilingual film, the Tamil version called Kutrappirivu), costarring Srikanth and directed by debutant Manmohan.