Laxman's return to the party was cleared by the Congress high-command, after which his elder brother Digvijaya Singh proposed his membership which was then accepted by Hariprasad.
Laxman, who had left the party in 2003 after Congress lost the assembly elections in Madhya Pradesh, had joined BJP and won 2004 Lok Sabha elections, but lost in 2009.
He was later expelled by the BJP for anti-party activities after he criticised the party president Nitin Gadkari for making some remarks against his family.
"I will work for the party with full dedication and strength," Laxman told PTI, adding, there was a lot of pressure from the Congress workers to join the party.