Rahul was unanimously named for the post of the Congress president on Monday after no one else from his party challenged him in the internal election.
The elevation of Rahul from the post of vice president comes at a time when the party finds itself in a severe political crisis. The transition bears an uncanny resemblance to the time when Sonia took over as the Congress' president and the party clocked its worst performance since Independence in the 1999 elections, winning 114 seats.
The Congress bounced back in 2004 and retained power in 2009 - it also won a string of Assembly elections from 2004 to 2014.
The timing of Rahul's promotion is somewhat similar as nearly all the exit polls have predicted the Congress defeat against the Bharatiya Janata Party (BJP) by a large margin in the recently concluded Gujarat and Himachal Pradesh elections.
Results for both the state elections will be declared on Monday.
Rahul led the Congress campaign for the first time for Gujarat elections where the final phase of voting was held on December 14.
Rahul's promotion caps years of speculation about his new role in the Congress. In October, Sonia broke her silence on her son’s proposed elevation in the party and said, on the sidelines of a book launch, “Rahul Gandhi will be Congress president soon”.
Before officially taking the baton as the Congress chief, Rahul started fitting himself in the shoes of the party president.
It was Rahul who had rebuked veteran leader Mani Shankar Aiyar and the Gandhi family loyalist when he scored a goal against his own team with his "neech aadmi" comment against Prime Minister Narendra Modi and later decided to suspend him.
Rahul Gandhi was elevated as the party's vice president in January 2013 and has since then, operated as the party's vice president.
Sonia Gandhi, 70, the party's longest-serving chief, has been keeping unwell in recent years and had scaled back her public engagements, pushing Rahul to the fore.
Sonia is expected to continue to head the Congress Parliamentary Party.
Asked what role she would play after her son's elevation, Sonia on Friday said, "My role is to retire".
An atmosphere of celebration gripped the Congress headquarters in New Delhi. Posters and hoardings were put up around the All India Congress Committee ahead of Rahul taking charge as the party’s president. Party workers burst crackers and raised slogans in support of Rahul outside the headquarters at Delhi's Akbar Road.