Uday Shetty (Nana Patekar), Majnu (Anil Kapoor) and their boss, Sikander (Feroz Khan) are basically three Hong Kong-based serio-comic mobsters, who are keen to get their sister Sanjana (Katrina Kaif) married into a respectable family.
Uday, who accidentally meets the handsome bachelor Rajiv (Akshay Kumar), gets convinced that the latter would be an appropriate match for Sanjana . However, Rajiv's uncle, Dr. Ghunghroo (Paresh Rawal) disapproves of Uday's association with a dubious family.
Meanwhile, Sanjana, who is totally unaware of her brother's plans, meets Rajiv on a cruise and they fall in love. She has the acceptance of Dr. Ghunghroo, who is unaware of the fact that she is the sister of the mafia. When Dr. Ghunghroo realizes his faux pas, he tries to escape the fury of the brothers.
What follows after that, is a commotion of comically funny situations, as each of the diametrically different brothers gets engaged in smart and comic stunts to get their uncle agree to the alliance.
The entire plot takes a U-turn when a stunning bombshell (Mallika Sherawat), arrives on the scene and claims to be Rajiv 's fiancée which only adds to the hullabaloo and chaos!
Produced by Firoz Nadiadwala and directed by Anees Bazmee, Welcome has music by Himesh Reshammiya/Anand Raj Anand and the movie is slated for December 21 release.