Priya Malhotra (Kareena Kapoor) is an orphan who hopes to have a family of her own and keeps a diary outlining her dreams and the type of man she wants to meet – someone who does not drink, smoke or tell lies. She is skeptical when her friend Honey's (Delnaaz Paul) aunt, a card reader, Sunita Rao (Kirron Kher), predicts that she will go to a foreign land and find the love of her life in seven days. She is pleasantly surprised when she is selected to go to a Youth Festival in Bangkok.
That is where Amit (Shahid Kapoor) enters. Amit is a complete opposite to what Priya wants in a guy. He smokes, drinks, and lies. Due to his bad habits, Amit is being chased by security and runs into Priya's hostel room. Before he leaves, he sees Priya and falls in love with her. He takes her diary and escapes. He then pretends to be the total guy Priya wants to be with, and the two start a relationship. Soon enough, Priya spots her diary in his room, and realises he had stolen her diary and acted to be like her dream man. She breaks up with him, and leaves the country to go Delhi and forget about her past.
After she reaches the airport, Amit also arrives, and explains to her that destiny wants them together. Priya does not believe him and therefore challenges him that if destiny did want them together, they would both find them again in future. In order to prove it, she asks Amit to write his name and phone number on a note and uses the same note to buy a Numerology book, in which she writes her own name and phone number and further she sells it in market at second hand rate.
If she receives the same note again and if Immy finds that book with her name and number on it, then it will prove that they love each other and its destiny that wants them together. Three years later, Amit is engaged to Sofiya (Aarti Chhabria) and Priya is engaged to Jatin. However, a week before the marriage, both of them land up in Delhi again looking for each other.Shahid Kapoor as Amit 'Immy' KapoorKareena Kapoor as Priya MalhotraAarti Chhabria as SofiyaKirron Kher as Sunita RaoSarfaraz Khan as AshishDelnaaz Paul as HoneySatish Shah as Trilok KapoorHimani Shivpuri as Mrs. GandhiSatish Kaushik as Rosan Saputra
In 2004, the cast began shooting in places like Delhi and Dubai, and later continued to shoot at Pathways World School. They were also supposed to shoot in Thailand, but Kapoor asked for a delay to attend the premiere of Dil Maange More, thus avoiding the 2004 Indian Ocean tsunami that destroyed the hotel that the cast and crew had been scheduled to stay in. The movie was expected to hit screens on 23 December 2005, but due to some financial and casting problems, it failed to do so. Salman Khan was signed on to do an important extended guest appearance for the film but opted out because of differences with the film's lead pair (Shahid Kapoor and Kareena Kapoor).
After the lead pair broke up, sources indicated that they wouldn't come together to dub for the film. However, the director, Satish Kaushik questioned "...why should Shahid and Kareena have any problems dubbing it?" Producer Boney Kapoor further noted that "...perhaps it was destined that the most romantic film featuring Shahid and Kareena would come after their relationship." In December 2007, sources indicated that the film was scheduled to release the day after Valentine's Day (15 February 2008) but it was again delayed. On 1 April 2008, the director announced that Shahid Kapoor had begun dubbing for the film whilst Kareena Kapoor would begin after she returned from her overseas trip. In February 2009, it was reported that both the actors had finally completed dubbing for the movie.
Upon release, Milenge Milenge received mixed to negative reviews from critics. Rajeev Masand of CNN-IBN gave the film a rating of 1.5 out of 5 and described the film as "regressive, senseless, and packed with plot-holes the size of craters". Taran Adarsh of Bollywood Hungama rated it 2/5 and said, "Milenge Milenge has the charismatic lead pair, who are very popular with the youth, as its USP. But the problem is its dated look. Having taken a long time to reach the theatres, it will have to rely on a solid word of mouth to lure the audiences into cineplexes". Mayank Shekhar of the Hindustan Times gave it 1.5/5 saying, "Years since, while the film's main pair may not be friends anymore, have probably knocked each other off their Facebook pages, trashed old kissing pics, tucked away the sweet SMSes, they can’t quite disown a new release that celebrates them still. Well. Sucks. I guess!". Gaurav Malani of Indiatimes gave the film 2/5 and stated, "Watch it only if you are just interested to see Kareena Kapoor when the term size zero wasn’t coined. Else Milenge Milenge doesn’t score too much above zero".
The film opened to a poor opening and collected ₹11 crore (US$1.7 million) in its theatrical run.