Sonam, who played the brave heart in biopic Neerja, wrote, "You are always going to be a guiding light in darkness. You've inspired me in more ways than one."
The 31-year-old actress also posted a picture with Neerja's mother Rama Bhanot. Read the whole post here:
Happy birthday Neerja, I'd rather celebrate your birth than any other day... You are always going to be a guiding light in darkness. You've inspired me in more ways than one. Playing you has taught me compassion, patience, kindness and most importantly self-worth. Thank you and happy birthday laddo.
Neerja Bhanot was killed in the 1986 hijacking of Pan Am Flight 73 in Karachi. Ms Bhanot, who was 23 at the time, died while shielding a group of children from gunfire. She became the youngest recipient of the Ashok Chakra, India's highest peacetime gallantry award.
Her story was turned into an acclaimed film by director Ram Madhvani in February.
Sonam Kapoor will next be seen in Veerey Di Wedding, with Kareena Kapoor Khan, Swara Bhaskar and Shikha Talsania.