Prithviraj was born in Trivandrum, Kerala, to Malayalam actors Sukumaran and Mallika. His elder brother Indrajith Sukumaran and sister-in-law Poornima are also film actors. His initial schooling was at St.Mary's School Poojappura, which was near to his Chengallur home. Here he acted in various dramas and skits for the annual day celebrations. Later he did his schooling from the Sainik School, (Kazhakoottam, Thiruvananthapuram) and Bharathiya Vidya Bhavan, Thiruvananthapuram. Prithviraj, along with his brother Indrajith, used to take part in debates and elocutions in the school. Prithviraj had also won the title of "Mr LA Fest", in 1999 at LA Fest, an annual inter school Arts Festival hosted by Loyola School, Thiruvananthapuram.
While pursuing his Bachelor's in Information Technology at the University of Tasmania, Australia, he was called by Renjith to play the lead role in his directorial debut Nandanam. It was Fazil, a leading Malayalam film director, who introduced him to Renjith. Following a decent performance in Nandanam he was flooded with offers from the industry that he decided to take a break from studies and concentrate on acting.
Prithviraj began his career in Malayalam cinema in 2002. The 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. He has been offered a role in the multilingual film 19th Step starring Asin and Japanese actor Tadanobu Asano, scripted by M T Vasudevan Nair and directed by Bharath Bala in association with Walt Disney.
Prithviraj was cast by Renjith in his second directorial ventureNandanam. After this he appeared in films directed by Lohithadas, Vinayan, Kamal and Bhadran.
He performed in Stop Violence and Swapnakoodu. Shyamaprasad, who cast him in lead role in hisfilm Akale, said that Prithviraj's advantages are his talent and intelligence irrespective of his box office successes. He played the role of Sub Inspector Solomon Joseph in Vargam.
In 2006, Lal Jose's Classmates was released. After Vargam, Prithviraj acted in another film 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.
In 2007, he starred in Chocolate directed by Shafi. 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 Manchadikkuru which is scheduled for release in 2009. The success of Prithviraj's Puthiya Mukham directed by Diphan led the Print & Visual Media to anoint him as Superstar. Following Robinhood directed by Joshy, Kerala Cafe is his latest release. His upcoming Malayalam projects include Raghupathy Raghava Rajaram and Thanthonny. He is also being cast in the lead role for the film titled Punyam Aham produced and directed by Raj Nair.
Prithviraj has debuted as a singer in Puthiya Mukham. He sang the title song of the film.
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 that "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 as: “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.
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. His first straight Telugu release would be Police Police (a Tamil and Telugu bilingual film, Tamil version called Kuttra pirivu), co-starring Srikanth and directed by Manmohan.
2009 Jai Hind TV Awards - Best Actor for Thalappavu and Thirakkatha
2008 Idea - Mathrubhumi - Amrita Film Award for 'Youth Icon of the Year'.
2007 Sathyan Memorial Award for Best Actor.
2007 Mathrubhumi - PSS Most Popular Actor Award sponsored by Federal Bank.
2006 Kerala State Film Award, Best Actor for Vaasthavam.
2005 Thikkurushi Award, Best Actor for Akale.
2004 Mathrubhumi - Special Jury Award for Akale.
2003 Film Critics Award, Best Actor for Meerayude Dukhavum Muthuvinte Swapnavum and Chakram.