Sivaji, an Indian software architect, returns to India from the United States. He aims to establish a non-profit trust called Sivaji Foundation, which includes a network of hospitals and educational institutions that serve the poor free of charge. An influential businessman, Adiseshan, sees Sivaji as his competitor because he runs profit-making educational institutions and hospitals. Sivaji is forced to bribe the corrupt civil service, but eventually, the bribes demanded become so high that he has to mortgage his house and sell his car to pay them. When Sivaji goes to court, he loses the case filed against him by Adiseshan regarding the methods Sivaji had used to open his foundation as a result of bribing numerous government officials. Simultaneously, Sivaji falls in love with a girl named Tamizhselvi. However, upon asking for his horoscope, an astrologer warns that their union will result in Sivaji's death. When Tamizhselvi refuses the proposal due to her concern for Sivaji, he calms her fears and convinces her to marry him.

Following the loss in the court case, Tamizhselvi requests Sivaji out of fear not to come for her again. Sivaji is reduced to utter poverty. Realising that the methods he used are unlikely to work again, he decides to play the game his own way. Sivaji, with the help of his uncle Arivu, acquires evidence of ?2 billion worth of illegal earnings in Adiseshan's possession and uses the documents to blackmail Adiseshan into giving him half the money. He further obtains details on people who have illegal earnings across Tamil Nadu and blackmails them to give him half of their illegal wealth. He then transfers the money to the bank accounts of his friends around the world by "hawala" forgery. They then deposit the money as donations to Sivaji Foundation, making the money usable and legitimate.

Sivaji informs the Income Tax Investigation and Vigilance Department about the details of the illegal money held by the tax evaders (including Adiseshan) and gets them arrested. He reopens the foundation and soon is able to provide free, good quality education, infrastructure, services and employment to people in every district of Tamil Nadu. Led by Adiseshan, those who were blackmailed by Sivaji exploit Tamizhselvi's innocence to silence him. Fearing for Sivaji's life, she hands over Sivaji's laptop to the CBI and Income Tax officers hired by Adiseshan with all the information regarding the illegal money transactions. With presentable evidence, Sivaji is arrested.

Adiseshan and the police order Sivaji to unlock his laptop. When Sivaji refuses, Adiseshan tortures him, leaving him for dead. To cover this up, Adiseshan and the police organise for thugs to shoot at the police van that will carry Sivaji's body, making it look like a murder by a third party. Sivaji, however, is faking; he was informed of the plans to kill him by a sympathetic police constable prior to the interrogation. Left alone in the room, he electrifies himself. Sivaji's friend Dr. Chezhian, Tamizhselvi and Arivu intercept the police van after being informed by Sivaji through a MMS and replace Sivaji's body with a dummy before the thugs open fire. While everyone thinks that Sivaji is dead, Chezhian revives him using a defibrillator. Following Sivaji's "death", Adiseshan and the CBI still try to open Sivaji's laptop by trying to fool the voice-detection program; they fail and all the data in the laptop is erased.

A few days later, while everyone wonders about the future of Sivaji Foundation, the revived Sivaji returns to take control of the foundation in the guise of an NRI friend, M. G. Ravichandran. Though Adiseshan immediately realises that Ravichandran is actually Sivaji, he is unable to prove this to the police due to the proof of Sivaji's "death" and Ravichandran's identity. Later, Sivaji confronts Adiseshan and the two fight atop the terrace of Adiseshan's medical college. During the fight, Adiseshan inadvertently strikes the campus's terrace roof causing money hidden in it to fly around the campus. The students spot the money and go after it, causing a stampede in which Adiseshan is killed. Sivaji Foundation soon becomes a frontier for India's economic and industrial rise.

Development

Following the success of his film Jeans (1998), S. Shankar wrote a script for his next film titled Mudhalvan (1999) having Rajinikanth in mind for the lead role. However, Rajinikanth could not act in the film due to schedule conflicts with Padayappa (1999). Hence the role went to Arjun Sarja. Post Anniyan (2005), Shankar decided to take a break before preparing for his next project.

In August 2005, Rajinikanth signed up for his next film which was to be produced by Chennai's oldest operative studio, AVM Productions, which was run by M. S. Guhan and M. Saravanan. This time Shankar was confirmed to be the film's director. After consulting Sivaji Ganesan's family to avoid any issues with the film's name, the project was subsequently announced on 24 August 2005. The film was titled Sivaji, after Rajinikanth's name at birth – Sivaji Rao Gaekwad. A tagline, The Boss, which stands for "Bachelor of Social Service", was suffixed to the title.

In addition to being AVM Productions' 168th film, Sivaji was also Rajinikanth's 154th film, his 100th Tamil film and his ninth film with AVM Productions. According to Rajinikanth's biographer Naman Ramachandran, the film was also made to commemorate the 100th birth anniversary of the production company's founder, A. V. Meiyappan. Sivaji was also noted for its change in the traditional yellow coloured Rajinikanth introductory text which made its debut with Annamalai. Instead the text is displayed in Chrome.

Cast and crew

In October 2005, Shankar and Rajinikanth announced that actress Shriya Saran would play the female lead role. Saran's voice was dubbed by actress Kanika, who was selected after a successful voice test, thereby collaborating for the second time with Shankar. Actor Vivek was signed up for the role of Sivaji's maternal uncle, Arivu, in November 2005. Actress Sunaina made her acting debut through this film in a special appearance; the scene however was later removed from the final cut. Nayantara, who had earlier worked with Rajinikanth in Chandramukhi, was signed up to perform alongside Rajinikanth in the song "Baleilakka".

Suman was confirmed in March 2006 to play the role of Adiseshan after Amitabh Bachchan, Prakash Raj and Mohanlal were considered. Sathyaraj said he declined the role because, "After a film of the calibre of Mr. Bharath with Rajnikanth, I couldn't settle for anything less. So I didn't accept Sivaji." For his role, Suman removed his moustache and used dentures to make his smile visible. Shankar instructed one of the costume designers to give the character a spotless white dhoti, shirt, shoes, a Rolex watch and Ray-Ban sunglasses. Prior to this, Suman had acted with Rajinikanth in Thee (1981). Subbu Panchu Arunachalam, son of filmmaker Panchu Arunachalam, dubbed for Suman. Debate speakers Solomon Pappaiah and Pattimandram Raja were selected to play supporting roles making their cinematic acting debut. Vadivukkarasi and Manivannan were selected to play Sivaji's parents. Raghuvaran appeared in a small role as Dr. Chezhian.

Shankar, who also wr