‘Ramaiya Vastavaiya’ is about Ram (Girish Kumar), a rich, city boy, born to billionaire parents and brought up in Australia and Sona (Shruti Hassan), a traditional, simple desi girl from Punjab who is brought up by her only brother, Raghuveer (Sonu Sood). He is heartbroken when their father marries another woman and throws them out of the house, humiliating them on the way. Their mother dies and her tomb is built on the small land which they own until the zamindar tells them that it is his land, since their mother had taken a loan from the man. Raghuveer volunteers to work day and night, to pay off the loan as long as they don't tear down his mother's tomb. The Zamindar agrees and the local station master helps them. Slowly Raghuveer and Sona grow up. One day, Riya, Sona's best friend, comes to their house to invite Sona to their house as she is getting married. Riya's cousin, Ram also arrives on the same day with his mother, Ashwini (Poonam Dhillon).

Slowly Ram and Sona fall in love but Ram's mother does not bear it as Sona is not as rich as them, and is thus not to their standards; Ram is also to be married to Ashwini's brother's business partner's daughter, Dolly. Ashwini humiliates Sona as well as Raghuveer, who arrives a minute before, and both are thrown of the house after Ashwini accuses them of trying to entice and trap Ram. When Ram learns of this, he goes to Sona's house and pleads to her brother to accept him. Raghuveer gives him a chance, just like he was given a chance by the Zamindar when he was little. Ram is tasked to take care of the cows, clean up after them and grow more crops than Raghuveer by the end of the season; if he does not, Ram will be thrown out of the village and can never see Sona again. The Zamindar and his son is not happy as the Zamindar's son wanted to marry Sona. With them and Dolly and her father trying to get Ram to lose the competition, Ram has to work hard for his love, eating red chillies and rice everyday, even though he can't bear it. Through many antics from the Zamindar's side and Dolly's side, Ram eventually proves his love for Sona to Raghuveer, and succeeds in growing more grains. However, Zamindar & his son kidnap Sona and then later tries to rape her. A fight takes place in which Ram kills the Zamindar's son. Raghuveer, after realizing that Ram and Sona should be together, takes the blame for this and spends seven years in prison. The movie ends with Raghuveer's release from prison which is also when Sona and Ram get married, in everyone's presence. Ashwini then accepts Sona to be her daughter-in-law.