Addressing an election rally in Bangalore Sunday, Kejriwal rubbished Modi's claims of putting Gujarat on a strong economic footing and crushing corruption in the state.
He accused Modi, still the Gujarat chief minister, of promoting "crony capitalism".
In a decision aimed at winning the maximum number of Uttar Pradesh's 80 Lok Sabha seats, the BJP has fielded Modi in Varanasi, one of the holiest of places for Hindus.
The BJP won only 10 Lok Sabha seats in 2009, a performance that eventually spiked its chances of ousting the Congress-led UPA in New Delhi.