Congress leaders, including former Prime Minister Manmohan Singh, and scores of party activists turned up at the Congress headquarters in the heart of the capital to greet him on his birthday.
Modi, who was engaged in a bitter war of words with Gandhi during the Lok Sabha battle, tweeted: "Best wishes to Rahul Gandhi on his birthday. May he be blessed with good health and a long life."
Gandhi responded warmly: "Thank you for your greetings Narendra Modiji. I appreciate them."
Congress supporters got into a celebratory mood, dancing to the beat of drums in the morning outside the Congress office on Akbar Road here.
There were similar scenes outside 10 Janpath Road, his mother and UPA Chairperson Sonia Gandhi's residence where Youth Congress members led the celebrations.
Rahul Gandhi arrived at the party office with a packet of sweets, which he distributed among the media persons.
He then cut a cake along with the party workers.
Manmohan Singh, Rahul Gandhi's sister and General Secretary Priyanka Gandhi, Rajasthan Chief Minister Ashok Gehlot, General Secretary K.C. Venugopal, Ghulam Nabi Azad and others poured into the party office and greeted Rahul Gandhi.
Former Madhya Pradesh Chief Minister Shivraj Singh Chouhan said: "I wish Congress President Rahul Gandhi happy birthday."
Congress spokesperson Randeep Singh Surjewala tweeted: "Your indomitable courage in face of every adversity, your indelible commitment to principles in face of every onslaught, your simplicity and straight forwardness when being Machiavellian is often considered a virtue is what endears you and sets you apart. Happy Birthday Rahul Gandhi."
Rahul Gandhi tweeted: "Thank you all for your best wishes and greetings on my birthday. I am overwhelmed and grateful for your love and affection."
Rahul Gandhi was born on this day in 1970 to Rajiv Gandhi and Sonia Gandhi.
He has been elected to the Lok Sabha from Wayanad in Kerala but was defeated in Amethi. Under his leadership, the Congress won only 52 Lok Sabha seats, forcing Rahul Gandhi to say that he wants to give up the party's presidency.
( With inputs from IANS )