Pokkiri movie begins with Tamizh(Vijay), a local goon who will kill anyone, anytime for money, being chased by Mallesh, a member of Ali Bhai's gang and his henchmen. Tamizh has taken a contract from Narasiman to beat up Mallesh, which he does successfully (Aadungadaa). Impressed by his ability to handle a seasoned gangster like Mallesh and his henchmen, Guru invites Tamizh to join Ali bhai's gang. Tamizh declines the offer stating that he does not work for any gang, but is ready to do anything, given enough money. Meanwhile, Tamizh encounters Shruthi(Asin Thottumkal) when he visits his friend's father(Nassar) aerobics class.
He is bowled over by her beauty, though she disregards him as a thug. Shruthi a college going student, lives with her widowed mother and younger brother. Body Soda(Vadivelu) , is a cowardly kung fu master who lives next-door to Shruthi, and is the main source of comic relief of the film. He is trying to win her heart, but has had trouble doing so. Sub inspector L. Govindan(-), is a corrupt, perverted officer in the colony where Tamizh and Shruthi live. He goes hand in glove with the land mafia, often helping them out in their activities. He is also on the payroll of Ali Bhai. He is also a lecherous man, whose eye falls on Shruthi and he decides to make her his mistress.
Tamizh's first assignment with Ali Bhai's gang is to kill a member of Narasiman's gang. However, police show up at the spot where Tamizh and the other gangsters are waiting for the kill. Tamizh distracts the cops long enough for the others to finish the task and flee. He also helps Shruthi escape from L. Govindan, in the middle of all this. She is impressed by his kindness and starts developing friendship (Vasaantha Mullai) with him. He also starts having feelings for her, which are reciprocated by Shruthi (Dole Dole). When she expresses her feelings towards him, they are attacked by members of Narasiman's gang, whom Tamizh single handedly finishes off. Shruthi is shocked to learn that Tamizh is a seasoned gangster and has no qualms in killing people.The movie concludes with Sathyamoorthy/Tamizh avenging his father's death by finishing off all members of Ali Bhai's gang including Ali Bhai and his henchmen.