The former Bharatiya Janata Party (BJP) MP was warmly into the party by Congress vice president Rahul Gandhi.
Sidhu’s wife Navjot Kaur Sidhu had earlier joined the Congress.
A smiling Gandhi and Sidhu later posed for photographs.
“Beginning of a new inning. On the front foot... Punjab, Punjabiat and every Punjabi must win!!!” the former India opener said in a tweet later.
Sidhu is expected to contest the February 4 Punjab assembly election from Amritsar East, part of the Amritsar Lok Sabha constituency which he represented for the BJP from 2004 to 2014.
Congress spokesman Randeep Surjewala said the party “welcomes Sidhu and thanks Gandhi for bringing like-minded leaders under the Congress umbrella”.
Former Punjab chief minister and state party chief Amarinder Singh congratulated Sidhu by phone from Bathinda, saying his induction would strengthen the Congress in Punjab.
“Besides being the party’s choice for Amritsar East, Sidhu, who is known for his wit and humour besides being strongly nationalist, is the star campaigner in the Punjab polls,” said a statement from Amarinder Singh’s office.
The BJP said Sidhu was boarding “a sinking ship”.
“Sidhu is a great colleague. I hope he doesn’t get drowned in a sinking ship,” said BJP leader and Minister of State for Home Kiren Rijiju.
The Aam Aadmi Party (AAP) immediately began poking fun at Sidhu, replaying videos of earlier times when he used to viciously attack the Congress.
AAP leader and Delhi Chief Minister Arvind Kejriwal, who is now campaigning in Punjab, has said Sidhu has been roped into the assembly battle because Rahul Gandhi doesn’t like Amarinder Singh.
The Akali Dal dismissed the development as of no significance, saying it would make no difference to the electoral outcome.
Sidhu, who had earlier toyed with the idea of joining the AAP along with his wife, met Gandhi on Friday too to discuss his role in the party.
Sidhu, who never enjoyed warm relations with the Akali Dal, quit the BJP saying he was feeling stifled.
He also told friends that the BJP did not field him from Amritsar in the 2014 Lok Sabha election under pressure from the Akali Dal.
The BJP instead fielded current Finance Minister Arun Jaitley, who lost the election to Congress leader Amarinder Singh.
