He told the media he was confident of winning with a record margin.
"I will repeat my past world record," Paswan said. "People have been supporting me and will vote for me."
Paswan faces 93-year-old Janata Dal-United candidate and sitting member Ram Sunder Das, who is also a former chief minister.
Paswan's wife Reena Paswan and son Chirag Paswan were present at a public meeting he addressed soon after filing the papers.
The LJP joined the BJP-led National Democratic Alliance in February, after a gap of 12 years. The party is contesting seven parliamentary seats in Bihar.