Pappu Yadav will take on Janata Dal-United chief Sharad Yadav, who was elected to the Lok Sabha from Madhepura in 2009.
Also on Monday, the RJD was jolted when its leader in the Bihar legislative council, Ghulam Ghouse, joined the ruling JD-U. He is likely to contest from Madhubani.
Pappu Yadav thrice won the Lok Sabha polls from Purnia - 1991, 1996 and 1999 - and once from Madhepura (2004).
His wife and former MP Ranjita Ranjan is contesting on Congress ticket from Supaul.
Last year, citing lack of evidence, the Patna High Court acquitted Pappu Yadav in a case related to the killing Communist Party of India-Marxist leader Ajit Sarkar in May 1998.