The celebs took to micro-blogging site Twitter to wish the actress.
Rhea tweeted: "Gearing up for @sonamakapoor's birthday. This means ordering the most indulgent chocolate cake ever and then convincing her that its 'diet' (sic)."
To which, Sonam added: Sitting with my family is the most special thing ever! Thank you @RheaKapoor @moh_m arjun, shehlu @anshulakapoor and kunal.. And mom! Love u."
Maheep Kapoor, who is married to Sonam's uncle Sanjay: Happy birthday to my stunning niece @sonamakapoor.
Neil Nitin Mukesh wished her singing the birthday, "Happy birthday to you, happy birthday to you dear sonam, happy birthday to you".
Celina Jaitly: Happy birthday@sonamakapoor big hug.
Madhur Bhandarkar: Many happy returns to @sonamakapoor God bless.
Designer Manish Malhotra posted: Wishing you a very happy birthday.
Designer Nachiket Barve: Wishing @sonamakapoor a sparkling birthday! Hope its super fun and the year ahead even better! Xx.
Sonam, eldest daughter of actor Anil Kapoor and designer Sunita Kapoor, made her acting debut alongside Ranbir Kapoor in Sanjay Leela Bhansali's "Saawariya" in 2007. After that, she featured in Rakeysh Omprakash Mehra's "Delhi-6" with Abhishek Bachchan and later teamed up with Abhay Deol for the romantic comedy "Aisha", which was produced by her sister Rhea.
In 2010, she also appeared in Punit Malhotra's "I Hate Luv Storys" opposite Imran Khan.
Kapoor's forthcoming releases include "Mausam" with Shahid Kapoor and multi-starrer "Players" that stars Bobby Deol, Bipasha Basu, Abhishek, Neil, Omi Vaidya and Sikander Kher.