Kundan Shankar (Dhanush) is the only son of Tamil Hindu Brahmin parents settled in Varanasi. Since his childhood, Kundan has had a strong and obsessive one-sided love for Zoya (Sonam Kapoor), a Muslim girl residing in the other neighborhood, whom he had seen doing namaaz in his teacher's house while he went to collect chandha or donation for Hindu festival, Dussehra. He always attempts to flirt or be around Zoya but gets slapped several times in the process. These acts of courtship from him were being done even without knowing Zoya's name. Zoya finally reveals her name after repeated asking and starts to like him a bit because of Kundan's consistency of affection and tells him to meet at a place. When they meet, she comes to know that Kundan is a Hindu brahmin and starts to avoid again because her family is orthodox, and she is sure that they won't agree for any intimate relationship like marriage. Her family comes to know that Zoya is liking some Hindu guy, and they decide to send Zoya to Aligarh for further studies. After Zoya moves to College for further studies forcefully, Kundan tries to impress Zoya's family members by assisting them with small-small home chores. Zoya gets into Jawaharlal Nehru University, Delhi and discovers a long-lost strength as she confronts and then falls for student leader, Akram Zaidi (Abhay Deol).

After eight years, Zoya returns to Varanasi, barely recognizing Kundan when she meets him again. Kundan again attempts to ask Zoya for her love but she is reluctant, revealing that she is in love with Akram. She urges Kundan to convince her family about her marriage with Akram. Kundan eventually agrees and gets their wedding arranged, promising Zoya that he will also marry someone else and forget her. He proposes to his childhood friend Bindiya (Swara Bhaskar), who has had a crush on him since childhood.

On the day of Zoya's marriage, Kundan finds out that Akram is a Sikh, whose actual name is Jasjeet Singh Shergill. This enrages him, as Zoya had used their religious differences to convince him that their match was not possible. He crashes the wedding ceremony and reveals the truth to Zoya's parents. Kundan is later informed that Zoya tried to commit suicide, and Jasjeet was mercilessly beaten by Zoya's relatives. At the hospital, Jasjeet tells Kundan that Zoya convinced him to portray himself as Muslim to marry her, a plan he should not have agreed to. While with Jasjeet, Kundan forgets about his own marriage ceremony with Bindiya, taking place that day, and is too late when he returns. Hurt and angry, Kundan's family disowns him. Jasjeet's parents take him back to his village. Kundan tries to redeem himself by taking Zoya to Jasjeet's village. There, he is devastated to find that Jasjeet has succumbed to his injuries, finally understanding that his one-sided love has resulted in an innocent man's death.

Kundan becomes a homeless vagrant and begins visiting various religious places and volunteering in their activities so that he can atone for his sins. During one such visit, a man advises him to do the right thing rather than run away from his sins. Motivated, Kundan locates Zoya to her university, where she is spearheading the political party "All India Citizen Party" (AICP), that had been created by Jasjeet. Kundan joins the nearby canteen and serves the party, while trying to get Zoya's attention. Over time, he becomes popular with the party due to his simple nature. They're also impressed when Kundan helps them in negotiating some tough situations by using his simplistic witty tricks. However, Zoya holds a grudge that the person who is responsible for Jasjeet's death is now taking his place. She tries to instigate party members against Kundan but Jasjeet's sister Rashmi (Shilpi Marwaha) tells Kundan to continue, as he is the best choice for fulfilling Jasjeet's vision.

Kundan, however, only wants Zoya to forgive him. The Chief Minister tells Zoya that she must get revenge on Kundan. To get back Jasjeet's position, she tells Zoya to let Kundan get injured as he delivers his campaign speech. Zoya apparently seems to get brainwashed by this plan and as the Chief Minister desired, Kundan is hurt badly and sent to ICU, thus fulfilling Zoya's revenge.

At a press meet, the Chief Minister denies having any hand in the blast that hurt Kundan. However, Zoya steps forward and reveals that the plan was plotted by her and the Chief Minister and that she is prepared to go to prison for this. Zoya then finds out that Kundan was aware of the plot and still let himself be injured. Shocked, she rushes to the hospital to be with him.

In a final voiceover, a dying Kundan wonders about letting go. He says he might have the desire to live again if Zoya called out to him, but then again, everything has become so tiring, he would rather let go and rest (euphemism for dying). He says that he can be born again and again in the same Varanasi, fall in love with a girl like Zoya again, and become a Raanjhanaa (Beloved one) in her love. Then he slowly dies.

• Dhanush as Kundan Shankar
• Sonam Kapoor as Zoya Haider
• Swara Bhaskar as Bindiya
• Mohammed Zeeshan Ayyub as Murari
• Abhay Deol in an extended special appearance as Jasjeet Singh Shergill alias Akram Zaidi
• Shilpi Marwaha as Rashmi Shergill, Jasjeet's sister
• Suraj Singh as Anand
• Kumud Mishra as Inzamaam Qalab-E-Haider a.k.a. Guruji, Zoya's father
• Saniya Anklesaria as young Zoya
• Arvind Gaur in a cameo appearance as Guptaji
• Sujata Kumar as Chief Minister
• Vipin Sharma in a cameo appearance as Shivraman Shankar, Kundan's father
• Ishwak Singh as Shahid, the doctor from Lucknow who is chosen a prospective groom for Zoya by Inzamaam
• Tejpal Singh as Ishar Singh Shergill, Jasjeet's father
• Nisha Jindal as a student of JNU
• Manveer Choudhary as a student of JNU
• Late Ginny Singh as a JNU activist

Development

In late 2011, Shahid Kapoor and Sonakshi Sinha were signed as the lead pair for the film. Apparently, they dropped out of the project because of Prabhudeva's next R... Rajkumar . In late January 2012, actor Dhanush, making his Bollywood debut, signed onto the film for the character of Kundan. The actor reportedly underwent training for fluency in Hindi language to obtain the role. Actress Sonam Kapoor was signed on for the role of the female lead after March 2012. In April 2012, the actress and the director visited the JNU Campus of Delhi for the former to imbibe more for her role. Sonam Kapoor also attended acting workshops with prominent theatre director Arvind Gaur to learn the nuances of street theatre. The director chose to cast actors who could also play younger versions of themselves. In an interview the director stated the film was an intense love story, and its characters would travel to Delhi, Punjab and Chennai, and that actor Abhay Deol would be seen in a special appearance in the film. Urmila Sharma, well known for her Hindi TV serial roles was signed to play the character of Kundan's mother in the film. Initially, Aditi Rao Hydari was supposed to play the role of Kundan's childhood friend but she opted out due to lack of availability, being replaced by Swara Bhaskar.

Characters

Actor Dhanush plays the character Kundan who has a deep passion for his city Banaras and Zoya. It depicts him a young boy and a teen who turns into a sensitive adult. Sonam Kapoor quoted her character as, "'Zoya' is childlike and unpredictable. She can be cold and at the same time, objective. She has every quality that makes her desirable to a man." In an interview, Kapoor revealed that for playing the role of a school girl in the film, she drew inspiration from the character Jaya Bachchan played in the 1971 film Guddi. Actor Abhay Deol as Akram plays a secure yet confident university student, socialist and a budding politician.

Filming

After main casting announcements, filming was substantially delayed; the reason was speculated to be composer A. R. Rahman's music being denied outright by the film director. Filming officially began in Varanasi, India in early September 2012 and continued for 40 days in and around the city. As per reports, the leading duo were also seen playing the role of 17-year-old teenagers. In mid-September 2012, the schedule of filming was put on hold as actor Dhanush fell ill on the sets in Varanasi. While filming in October 2012, the actor injured his shoulder during the filming of an action sequence for his Tamil outing Maryan. The consequences led to the scheduled shooting of dance sequences to be postponed and were shot in Varanasi on 19 December 2012. On 4 November 2012, Sonam Kapoor and Abhay Deol shot the song "Tu Mun Shudi" at India Gate, Delhi, and their dialogue scenes were shot at the Indian Institute of Mass Communication campus in Delhi by early December 2012. Permission to shoot inside was denied to the director by the college authorities. So, the unit shot some scenes in Amity International School, Noida. To avoid footage leaks, over a hundred potential crew members were made present at the filming venue. Certain filming was also done in Gurgaon and Faridabad. The title track of the film was shot on 27 December 2012. The final schedule of filming began in Delhi on 7 January 2013. In March 2013, the film's crew shot several scenes at the Pataudi Palace in Haryana over two days. After the completion of writing work, Actress Sonam Kapoor required the dialogue in Devnagri, hence "Sanjay Bhardwaj" (Dev) appointed to do the said job for her.

The music and the background score for the film was composed by A. R. Rahman. The soundtrack's original version has lyrics penned by Irshad Kamil whereas the Tamil version by Vairamuthu. In an interview with Hindustan Times, Rahman stated that he had emphasised the folk-classical genre as the film brings out a fascination for Benaras through the music and hence, most of the songs are character-driven. In all, the soundtrack album has nine original tracks. The original version of the soundtrack was released on the co-branded record labels Sony Music and Eros Music on 31 May 2013 and the Tamil version on 19 June 2013. The soundtrack received positive critical reception on release.

On 10 May 2013, a grand event was held at a set resembling Varanasi at Film City in Goregaon, Mumbai. The lead actors made their entry riding a chariot and performed the title track of the film. The producer stated that the event was promoted in Banarasi style so as to represent the essence of the film and its setting. The film's music was promoted at the Radio Mirchi Studios in Mumbai on 27 May 2013. Dressed in typical South Indian attire, Dhanush and Sonam Kapoor promoted the Tamil version of Raanjhanaa in Chennai. The leading duo promoted their film in Mumbai, Delhi, Ahmedabad, Lucknow and Jaipur from mid-May to June 2013.