Prime Minister Narendra Modi tweeted birthday greetings to Rahul Gandhi, on his 49th birthday, this morning. "May he be blessed with good health and a long life," PM Modi wrote on Twitter.
Mr Gandhi was also greeted by messages from well-wishers, party workers and supporters on social media resulting in #IAmRahulGandhi and #HappyBirthdayRahulGandhi becoming trending topics.
A Congress worker identified by news agency ANI as Phool Singh celebrated Mr Gandhi's birthday by organising a 'hawan' outside his residence in New Delhi.
Mr Gandhi will hope the words of cheer mark a turnaround in fortunes, for both himself and the party, after the opening six months of a year that saw the Congress thumped by the BJP in national elections.
The Congress led the way by posting a short video on Twitter looking back at "five moments when he inspired Indians everywhere".
Mr Gandhi was at the forefront of his party's campaign during elections in April and May, repeatedly taking on Prime Minister Narendra Modi over allegations of corruption in the Rafale fighter jet deal and coining the slogan "Chowkidar chor hai", as he sought to galvanise the Congress.
PM Modi and Mr Gandhi also sparred over his father, former Prime Minister Rajiv Gandhi, after PM Modi declared the former Prime Minister "bhrashtachari No 1'' (corrupt number 1)" during an election rally in Uttar Pradesh.
Mr Gandhi's response to PM Modi's remark was a hug, and a warning on "karma".
However, despite Mr Gandhi's best efforts, the Congress slumped to defeat in the election, winning only 52 seats to record a marginal improvement over the all-time low of 44 in 2014 polls.
The election also saw Mr Gandhi lose his parliamentary seat from the family stronghold of Amethi - a seat he held for three consecutive terms - to BJP leader Smriti Irani. He remains a parliamentarian though, having won from Wayanad in Kerala.
Mr Gandhi, who made his first visit to his new constituency earlier this month, took the opportunity meet Rajamma Rajappan, a retired nurse who was present at the time of his birth in Delhi 49 years ago. The Congress chief's Wayanad Twitter account shared a picture of him hugging the nurse.
The Congress leader's position as party president remains a matter of speculation after he submitted his resignation in May. There have been calls for Mr Gandhi, including one by former Delhi Chief Minister Sheila Dikshit, to retract his resignation and continue leadership of the party but, so far, he has remained firm.
Birthday wishes for Rahul Gandhi have begun flowing in, with the Congress leaders and the party's grassroots-level organisations among the earliest to wish him on his birthday.
Former Karnataka Chief Minister Siddharamaiah praised Mr Gandhi for his "commitment to the responsibilities & vision for inclusive development".
Rajasthan Deputy Chief Minister and close aide Sachin Pilot tweeted in Hindi, writing, "Happy Birthday to Shri Rahul Gandhi Ji, President of Akhila Bharatiya Congress Committee and best wishes for a bright future. I wish you good health and longevity with God."
Other wishes came from state units of the Congress, including grassroots-level organisations.