Polls close at 6:00 pm (1230 UT) in the seventh and final round of voting, ending the world's biggest election with 900 million eligible voters.
Long queues formed outside polling stations in eight northern states electing the final 59 candidates to India's 543-seat lower house.
Heavy security was imposed in West Bengal state, which has seen street battles between followers of Modi's Bharatiya Janata party and opposition groups.
Modi's constituency in Varanasi, the holy city in Uttar Pradesh state, was also among those to vote.
The conservative BJP has campaigned aggressively on Modi's strongman image and played up recent cross-border air strikes against Pakistan. But the opposition, led by the Congress party of Rahul Gandhi, have accused him of pursuing divisive policies and neglecting the economy.
All votes from the seven rounds will be counted on Thursday with the main trends to be announced the same day.