Pheu Thai is expected to get 173 seats for constituency MPs and none for party-list MPs, according to the poll.
Phalang Pracharat came in second with 96 seats, or 53 from constituency and 43 from party-list.
The Democrat Party, which came third, is likely to win 88 constituency MPs and none for party-list MP.
Future Forward is likely to become the biggest party to win for party-list MPs, with 47 seats plus two seats from constituency.
Bhumjaithai is likely to win the fifth place or 40 seats in total, or 21 constituency seats and 19 party-list seats.
The poll surveyed 79,521 respondents nationwide.
In this election, there will be 350 constituency MPs and 150 party-list MPs. The result of the party-list MPs will be known by Tuesday.
In previous elections, exit polls conducted after the poll proved to be inaccurate.