"I was reading in some newspapers that it will be a symbolic fight (in Varanasi) and it is Modi who will win," Kejriwal told a meting of Muslims here.
"I want to tell him (Modi) that I am going (to Varanasi) not only to fight but I am going to defeat him," he said.
Kejriwal said the Aam Aadmi Party's "success story" of Delhi would be repeated in the Lok Sabha election.
"In the Delhi (assembly) elections, nobody knew our candidates. But they defeated those who were MLAs for 20 years. I feel this will be repeated in the 2014 general election."
Kejriwal, who was repeatedly cheered, was addressing a meeting of Muslims attended by over 500 professionals and intellectuals.
There was a roaring approval when the former Delhi chief minister demanded to know who from among the audience will go to Varanasi to back him in the election.
Amid cries of "Inquilab Zindabad", scores of hands went up in the hall.
Kejriwal has said that he will hold a rally in Varanasi to decide if people want him to take on Modi, who the BJP has fielded in the Hindu holy town in Uttar Pradesh.