The story begins when Jenny (Jyothika) and Shiva (Vijay) are born in different states of India they meet as babies, when their parents left they were pulled apart. They are in their childhood and both want to represent their home town in a camp they are next to each other but don't speak or see each other. Ten years later, Jenny wants to pursue higher studies but her father wants her to get married. At first she gets angry at him but decides to marry according to her father's wishes. On the night of the wedding her groom elopes with his lover. Seeing Jenny depressed and disappointed, her father lets her study further. Shiva lives in a big city and is accepted to a college in Canada.
On the way to the airport, he gets in an accident and has to give up his dream of studying abroad. Shiva and Jenny enroll in the same college in different classes, they meet each other at a temple. They introduce themselves to each other and both say "I feel like I've seen you before". Then they meet again when Shiva's friend Babu is in love with a girl named Shanthi to give her a love letter Shiva goes to her house guarded. Shiva get out of his car and runs to Jenny when she walks out of Shanthi's house and explains to Jenny about the situation. So Shiva and Jenny work together to get Babu and Shanthi together. One day Shiva and Jenny have a very heated argument and this eventually hurts both of them especially Jenny. They try avoiding each other but can't because their friends need them to meet their lovers.
When they decide to forget about what happened and they try to get Babu into Shanthi's house but are caught and Shanthi's father ambush Jenny and Shiva while fighting Shiva close to being cut Jenny steps in to save him but her hands are bleeding and is taken to the hospital. Jenny gets better and find out that Shanthi is getting married and Shiva has a plan. As Babu and Shanti drive off to have their new life Jenny and Shiva say their goodbyes but not feelings. Jenny and Shiva miss each other and send a letter of love to each other through their co-passengers on the train which they are respectively going to board.Jenny reaches her village to find her marriage arrangements taking place but is pleasantly surprised to find that the groom is Shiva.
After watching the premiere show of Vaali, Rathnam offered S. J. Surya an opportunity to direct his next venture with Vijay and Jyothika being signed on soon after. Amisha Patel was also briefly considered for a role in the film, but was later not selected. Vijay began shooting for the film during the same time he was shooting for Fazil's Kannukkul Nilavu and revealed how hard it had been to shift between the two characters he was portraying.
Early reports indicated that the film would portray an illicit relationship where a young widowed mother (Mumtaj) would lust for the lover (Vijay) of her own daughter (Jyothika). The producer rubbished the rumors claiming that the film would be a romantic comedy.
The producers initially readied themselves to release the film on April 14, 2000 but pushed dates back to accommodate the release of bigger budget ventures such as Mani Ratnam's Alaipayuthey and Rajiv Menon's Kandukondain Kandukondain.
Rediff.com felt that "overall, the light, airy romance of Kushi works just right for the holiday season, with an appeal calculated for the teen and family audiences", praising the director's story-telling. Entertainment portal Bizhat.com gave the film a below average review and claimed that the film "does not justify the title in any way nor does it come anywhere near his first" and that it "is interesting in the beginning, but monotonous after a time as the narration gets stuck in a groove".
The Hindu featured the film as runner-up in their list of top Tamil films in 2000, placing it behind Vikraman's Vanathai Pola. Jyothika went on to win the Filmfare Best Actress Award in Tamil for her performance in the film. Deva won the Tamil Nadu State Film Award for Best Music Director in 2000 for his work in the film along with his work in Uyirile Kalanthathu and Sandhitha Velai.
In 2001, A. M. Rathnam re-signed Surya to direct the Telugu version of the film, also titled Kushi. The film starring Pawan Kalyan and Bhumika Chawla also similarly won positive reviews and commercial success. Surya also directed the Hindi version of the film in 2003 as Khushi for producer Boney Kapoor, with Fardeen Khan and Kareena Kapoor in the lead roles. The success of the lead pair's chemistry prompted Vijay and Jyothika to team up again in 2003 for Thirumalai, while the director and actor briefly reunited for a project titled Puli in 2005, before Vijay opted out. In an interview prior to the release of Anbe Aaruyire (2005), Surya revealed that the film was "like a sequel to Kushi".
The soundtrack of the film was composed by Deva, while Vairamuthu penned the lyrics for the songs. "Mottu Ondru" was based on "Why You Wanna Trip on Me" by Michael Jackson.