Venkata Ratnam Naidu, a young boy, lives with his younger half-brother (Ajay), stepfather Naidu (Nagineedu) and mother (Suhasini Maniratnam) in Kondaveedu, a village in Guntur District. His stepfather is always partial towards his half brother which constantly angers Venkata Ratnam. He starts to not care about what other people think about him, and renames himself after "Gabbar Singh", a popular antagonist character from Sholay. His anger towards his brother and father grows and he runs away from home. His stepfather, Naidu catches him and joins him in a boarding school away from Kondaveedu.
21 years later, a scene shows a gang of robbers trying to steal money from a bank in Kondaveedu, when Gabbar Singh (Pawan Kalyan), now a cop, tries to recover the money by beating up the robbers. It is revealed that Gabbar Singh is now posted as a Circle Inspector for the Kondaveedu region. His anger towards his brother and Naidu remains the same, and lives separately from them. He wants to live with his mother in his new house, but she instead wants him to stay with her and Naidu. Ajay is a gambling addict and has loans all over the village. Gabbar Singh falls in love with a handicraft vendor named Bhagya Lakshmi (Shruti Haasan), whom he chances upon during a police raid that he conducts against gambling.
It is revealed that the robbers who tried to steal are actually the henchmen of an upcoming politician names Siddhappa Naidu (Abhimanyu Singh). He with the help of his uncle (Tanikella Bharani) want to be a MLA of Kondaveedu. He meets Gabbar Singh and tries to appreciate him for catching the robbers. Gabbar Singh flatly refuses and tells Siddhappa that he actually knows who he is and tells him to behave himself.
Angered by Gabbar Singh's response, Siddhappa Naidu sends goons to disrupt the market yard in Kondaveedu. Gabbar Singh confronts the goons and defeats them with ease to reopen the market yard. Even more enraged, Siddhappa now plans to kill Gabbar Singh but his uncle instead advises him to speak with the Minister (Rao Ramesh) about transferring Gabbar Singh out of Kondaveedu. Siddhappa and his uncle meet the minister, who simply denies their request stating that Gabbar Singh is a sincere and honest cop and transferring him during the elections would be bad for the party. He also advises Siddhappa to make peace with Gabbar Singh or it would hurt his political aspirations.
Meanwhile, Gabbar Singh meets Bhagya Lakshmi and proposes marriage. She rejects it saying that she has to look after her father (Kota Srinivasa Rao), who is always drunk and she cannot marry while he is alive. Gabbar Singh then comes home to find his mother dead. He goes to his stepfather to make peace, as he is the only family left. His stepfather rejects and despises him as an outcast. Gabbar Singh is then attacked at the handicraft exhibition by Siddhappa's men, when he is with Bhagya Lakshmi; he kills all of them in a fight and goes to Siddhappa's house. He confronts Siddhappa and warns him to stop bothering him and tells him that he will not allow Siddhappa to become a MLA for Kondaveedu.
Provoked by Siddhappa's men, Gabbar Singh's brother hits one of his creditors brutally and injuring him. Siddhappa calls the police station to warn them about the fight. Gabbar Singh beats up his brother in public, thus disgracing him. Siddhappa decides to take advantage of the situation and suspend Gabbar Singh. He takes Gabbar Singh's brother and his father to the police station. But Naidu resolves the situation by accepting an apology from Gabbar Singh. Angered by the outcome, Siddhappa tells Gabbar Singh that something big will happen in the next 24 hours and tells him to stop it if he can. Gabbar Singh interrogates the henchmen of Siddhappa and finds out that Siddhappa arranged the marriage of Bhagya lakshmi with a local merchant by paying her father a lot of money. Gabbar Singh goes to the wedding and confronts Bhagya Lakshmi whether she loves him or not. Bhagya Lakshmi reveals her love and Gabbar marries her in the same event.
Siddhappa, as a last effort tries to bribe the high command to get a party nomination to contest in the election. He offers INR5 crores to get the ticket. Gabbar Singh comes to know of the arrangement and steals the money that Siddhappa sends to the high command. Gabbar Singh's brother in desperate need of money is approached by Siddhappa. He offers help and money and in exchange asks him to work for his elections. Siddhappa orders him to deliver a cellphone and a box of sweets to the Minister's house. But, unknown to him, a bomb is placed in the sweet box. After he leaves the house, it explodes, killing the Minister. Knowing that it was Gabbar Singh's brother who did the blast, the police commissioner (Jaya Prakash Reddy) suspends Gabbar Singh. Gabbar Singh confronts his stepfather Naidu tells him about his brother. Naidu suffers a heart attack after hearing the news and is hospitalized. Gabbar Singh takes care of Naidu at the hospital, thus bonding again. Gabbar's brother who is shocked by the events and the blast is convinced by Siddhappa to kill Gabbar before the later catches him. Although he has no intention to kill his brother, he accepts to do it to escape from them and meets Gabbar Singh. He confesses to Gabbar that he was sent to kill him by Siddhappa. He reveals to Gabbar that Siddhappa made him plant the bomb and that he never knew what was in the box. Gabbar tries to take him to the commissioner for a confession against Siddhappa. But Siddhappa calls Gabbar on his phone and reveals to him that he killed Gabbar's mother. In a final Battle, Gabbar arrives to Siddhappa's house and takes down the goons and kills Siddhappa. In the final scene it is shown that, Gabbar Singh hires most of the Siddhappa henchmen and gives them police jobs.