Bajirao Singham (Ajay Devgan) gets transferred to Mumbai and he discovers that one of his team members (Mahesh) is found dead inside an ambulance with massive bags of money. Bajirao decides to unearth the truth behind it and in this process, he collides with a powerful and fraudulent religious leader, Satyaraj Chandar a.k.a. Babaji (Amole Gupte), who has high-profile connections with corrupted politicians.
During this period, Guruji (Anupam Kher), is killed by Babaji, even though Singham was present at the scene. He vows revenge. Because of this, he has to pretend that he has resigned in front of his family. Due to this his father asks him and his childhood friend, Avni (Kareena Kapoor Khan), to come to their home town, Shivgarh. After some comic scenes, Singham and Avni, fall in love with each other. However, it is then revealed that Singham hasn’t resigned and came to Shivgargh on a mission to get some evidences against Babaji.
When they get back to Mumbai, Babaji starts threatening Singham’s family. He also harms all of Guruji’s candidates, including Avni, because her brother is one of the candidates. Singham manages to save everyone but before they resign, one of Babaji’s henchmen, Altaf (Pankaj Tripathi), wakes up from coma and testifies against him. Singham arrests Babaji and his left hand, Prakash Rao. However, some party workers execute an attack outside the court, killing the witnesses. This causes Babaji and Prakash Rao to receive bail. But after Babaji gets released, Singham goes to his house without wearing his police uniform and shoots at their buttocks to coerce them and the wounded Prakash Rao and Baba tell the truth.
A few weeks later, Guruji’s party wins the elections. While being transported to jail, Prakash Rao and Baba once again threaten Singham. Suddenly, the van in which Prakash Rao and Baba are being transported in suddenly stops and the driver walks away. A water tanker crashes into the van and both of them are killed. Inspector Phadnis (Vineet Sharma) tells media that there was a brake failure, and the incident is deemed an accident.