The film opens with a reporter entering into a small town that looks abandoned, with a statue of (Ranbir Kapoor). The reporter asks, where are the people of the town, the statue then narrates the story behind it.
Prem (also Ranbir Kapoor) is a free-loader who, while helping his friend elope, meets Jenny (Katrina Kaif). They both share the trait of stammering when they are emotional. In such a moment, the stammering Jenny induces a spontaneous stammer in Prem, which she misunderstands for mockery. Although this makes her dislike Prem initially, when she finds out his stammer is authentic, the two become friends. Prem eventually falls in love with Jenny, although she is oblivious to this and only considers him as a friend. When he tries to tell Jenny his feelings, he finds out that Jenny is in love with her college friend Rahul (Upen Patel).
He then meets Rahul and finds out that Rahul loves Jenny more than his family, so helps them board a train to escape. However, Rahul disappears at the train station, and Jenny returns to Prem so Prem can help her find Rahul.
As Rahul's father does not like Jenny and completely opposes relationship between Jenny and Rahul, mainly due to the religious barrier, Jenny being a Christian and Rahul a Hindu, when Prem visits Rahul's house for Jenny's proposal with Rahul, he is insulted by Rahul's father. Prem convinces his mother to let Jenny hide in their house while Rahul's family search for her, but they are eventually caught by the police. After that, Jenny lies to the police, claiming that she and Prem are in love, to save Rahul's name. While Prem corroborates Jenny's lie, he gets emotional and spurts out his true feelings for Jenny, which Jenny mistakes for over-acting.
Prem and Jenny successfully go to the club to get reunited with Rahul. Rahul tells Prem that he (Rahul) and Jenny are going to prepare the wedding in two days.
Unfortunately, a day before the wedding, Jenny gets kidnapped by Sajid Don (Zakir Hussain) who is seeking a ransom from Rahul's father in exchange for her.Prem and his buddies find her in Sajid Don's warehouse. A hilarious fight ensues between Prem and Sajid Don's gang. Prem's father (Darshan Jariwala) joins the fight, too. Later on, Sajid Don, a wanted criminal, gets arrested.
Rahul and his father, who's running for the elections, tell the media that it was they who were the ones involved in the fight with Sajid Don, intending to buy a good name for Rahul's father before the elections. On Jenny and Rahul's wedding day, Jenny finds out that Prem actually gave consent to Rahul and his father to publicize their false story. This and past recollections of Prem's selfless caring for her, makes her realize that she truly loves Prem and that Rahul and his family are actually very selfish, and prompts her to become a runaway bride. Meanwhile, Prem, who is about to leave the town is stopped by an stage actor (Behzaad Khan), who asks him to guide to an address, further driving him back to the church, where he finds Jenny as the actor disappears and it is revealed that he was actually Jesus Christ. She is united with Prem and the two happily get married, in a small celebration at a marriage registration office.
The statue in the beginning reveals that entire town is attending their wedding and asks the reporter to visit the registration office. Ranbir Kapoor as Prem Shankar Sharma and a statue (dual role)
Katrina Kaif as Jennifer Pinto (Jenny)
Salman Khan as Himself
Upen Patel as Rahul Jalan
Darshan Jariwala as Shiv Shankar Sharma (Prem's father)
Mithilesh Chaturvedi as Mr Pinto (Jenny's father)
Navneet Nishan as Mrs Pinto (Jenny's mother)
Smita Jaykar as Sharda Sharma (Prem's mother)
Shyam Mashalkar as Raju
Akul Tripathi as Kunnu
Khurshed Lawyer as David
Ameya Hunaswadkar as Lakhan
Pradeep Kharb as Tony Braganza
Sanatan Modi as Tony's father
Govind Namdeo as Pitambar Jalan
Dolly Bindra as Pitambar Jalan's wife
Mohan V. Ram as Pitambar Jalan's PA Sheshadri
Abhay Bhargava as Terror Tej Singh
Rati Shankar Tripathi as Bhairon Singh
Zakir Hussain as Sajid Don
Delhi Ganesh as Temple priest
Behzaad Khan as Lord Jesus (Special appearance)
Director - Rajkumar Santoshi
Producer - Ramesh S Taurani
Screenplay - Rajkumar Santoshi, R D Tailang
Cinematographer - Tirru
Creative Producer - Jay Shewakramani
Production Designer - Nitish Roy
Music - Pritam
Choreographer - Ahmed Khan
First Assistant Director - Manish Harishankar
Editor - Steven Bernard
Background Score - Salim-Sulaiman
Lyricist - Irshad Kamil, Ashiesh Pandit, Hard Kaur
Action - Abbas Ali Moghul, Tinu Verma
Sound Engineer - Rakesh Ranjan
Ajab Prem Ki Ghazab Kahani received generally positive reviews. Subhash K. Jha (film critic and author of The Essential Guide to Bollywood) states: "If you've ever wondered what on earth is on-screen chemistry here's your one-stop all-purpose encyclopedia on celluloid magic. Fasten your 'see'-it belts, as veteran filmmaker Rajkumar Santoshi sheds all his Lajja, and pulls out all stops to do a wacky goofy edgeless weightless comedy of characters who walk in and walk out of frames leaving behind fumes of old-fashioned funnies. Ajab Prem Ki Ghazab Kahani is an airtight trapeze down that familiar romantic lane." Nikhat Kazmi of the Times of India gave it four stars out of five and states: "The newly formented Ranbir-Katrina chemistry sets the screen on fire in this mad hatter's tea party. Adding to this is Pritam's peppy music score with Neeraj Shridhar, Atif Aslam, Hard Kaur, Sunidhi Chauhan and Mika raising a toast to high-spirited song and dance and Raj Kumar Santoshi penning some of the funniest dialogues in recent times and you have a great escape awaiting you at your favourite audi this weekend. Go, have a ball." Taran Adarsh of Bollywood Hungama gave the film four out of five stars arguing that it "entertains majorly" and that "the romantic moments are endearing. Most importantly, the on-screen chemistry is electrifying. Ranbir and Katrina look great together!" Noyon Jyoti Parasara of AOL India gave 3 out of 5 stars saying, "Its strong point, apart from Ranbir, happens to be its clichéd settings." Omar Qureshi of Zoom gave 3.5 out of five stars saying that "The main point to be noted in the film is that, the film is totally dedicated to love and all the things that are related to love and so, it will leave an ever lasting impression on youth." Minty Tejpal of Mumbai Mirror gave 3.5 out of five stars, saying that "It seems that Ranbir Kapoor can do nothing wrong. He is just fantastic through the film."
Mayank Shekhar of the Hindustan Times gave one star and said that "The film has no comic bone at all. There is certainly no romance either." Rajeev Masand of CNN-IBN gave it two stars and said that "Ajab Prem Ki Ghazab Kahani is a silly comedy that goes for slapstick gags and juvenile jokes that are hard to appreciate."
The film grossed Rs 920 million in India and 1.34 billion worldwide at the box-office. The film was declared as a blockbuster.2010, Winner, Filmfare Critics Award for Best Actor: Ranbir Kapoor
The soundtrack was composed by Pritam while lyrics were penned by Irshad Kamil and Ashish Pandit. The songs are remixed by DJ Suketu and arranged by Aks.
The soundtrack received generally favorable reviews from critics. Samir Dave of Planet Bollywood gave it a rating of 7.5/10 and said, "If you are looking for an enjoyable potpourri of different musical styles, and melody, then you will love what Pritam has served up for, "Ajab Prem Ki Ghazab Kahani". It deserves to be at the top of the charts". Joginder Tuteja of Bollywood Hungama rated it 3.5/5 and praised the music composer saying, "This is Pritam's year, delivering chartbusters by dozens all through the year, he can now look forward to another bountiful of hit songs up his sleeves with Ajab Prem Ki Ghazab Kahani. Also, Ranbir and Katrina can enjoy a hugely popular track for themselves in the form of 'Main Tera Dhadkan Teri'. Go, pick this one up from the shelves!". The songs 'Tu Jaane Na', 'Tera Hone Laga Hoon', 'Prem Ki Naiya' and 'Mein Tera Dhadkan Teri' became chartbusters.