'Chaahat' is an intense romantic drama that primarily revolves around Roop Rathore (Shahrukh Khan), an exceptional a singer in Bombay. His father was also a brilliant singer, but is now sick and in dire need of immediate medical care.
One day, while he is singing at Ajay Narang's (Naseeruddin Shah) hotel, Ajay's sister, Reshma (Ramya Krishnan) meets and falls obsessively in love with Roop. Reshma is a spoilt rich girl who demands everything and everyone to dance to her tunes, but Ajay looks through all of her wishes.
Roop is in love with a doctor named Pooja (Pooja Bhatt). Meanwhile, Reshma is obsessed with Roop, and asks her brother to call him again to sing in their hotel. But when she sees that all the girls are gaga over Roop, she gets very possessive, angry, and asks him to sing only for her now onwards. But Roop would rather work for rival, Patel (Shri Vallabh Vyas) than take this offer. Ajay's obsession with keeping his sister happy at all costs comes into play and Patel is brutally beaten until he agrees to throw Roop out of his hotel. Desperately in need of money for his father's operation, Roop has no option but to agree to Reshma's demands and is forced to break up with Pooja.
The operation of his father is successful, but his father is saddened by his situation and decides to leave Bombay. Roop later tries to leave Bombay himself, along with his father and Pooja, but his plans are interrupted when Reshma tries to commit suicide. Nevertheless, Pooja and Roop get married. Frustrated by the unsavoury turn of events, Reshma and her brother Ajay devise many plans to make their life miserable. How will Roop and Pooja deal with Reshma and Ajay's machinations? Will they ever be free to lead a happy and peaceful life?