Sarkar revolved around a don, Mumbai-based billionaire Subhash Nagre alias Sarkar (Amitabh Bachchan), who lives in a palatial house with his wife (Supriya Pathak), two sons Vishnu (Kay Kay Menon) and Shankar (Abhishek Bachchan) and his daughter-in-law Amrita Vishnu (Rukhsar). One day, a Dubai-based don, Rasheed (Zakir Hussain) tries to strike a deal with Sarkar, but he promptly refuses on moral grounds and also forbids him from doing it himself. Later, Rasheed tries to eliminate Sarkar's supremacy with the help of Sarkar's former associate Silver Mani (Srinivasa Rao Kota) and Swami Virendra (Jeeva).
In course of time, they trap Sarkar by assassinating a righteous, upright, political leader Motilal Khurana (Anupam Kher), an outspoken critic of Sarkar. Everyone, including his elder son Vishnu, believes that Sarkar is guilty but Shankar has deep faith in his father. Sarkar is arrested and jailed. Shankar then takes over the position of his father temporarily. Sarkar is later acquitted and remains bedridden.
Meanwhile, Silver Mani, Swami and Rasheed try to convince Vishnu, a foul-mouthed producer, to murder his father. Vishnu was previously thrown out of Sarkar's house because he had murdered a Bollywood actor for having an affair with actress Sapna (Nisha Kothari), whom Vishnu wanted to keep as mistress.
Vishnu returns home, pretending to have repented. When he approaches Sarkar at night to murder him, Shankar foils his plan and kills him. Shankar later eliminates all his enemies, including the Chief Minister Madan Rathore (Deepak Shirke) who also had a part in the attempt to end Sarkar and his rule. The closing scenes show people approaching Shankar for justice as his father apparently retires.