A total of 1.51 lakh persons were eligible to cast votes, officials said.
The polling for the Schedule Tribe constituency had started at 7 a.m. in 202 polling stations.
The election was necessitated as sitting Bharatiya Janata Party (BJP) legislator Vikram Usendi quit the seat after he was elected to the Lok Sabha from Kanker.
Chhattisgarh has always witnessed a bipolar contest between the ruling BJP and the Congress.
However, this by-poll is an exception as only two candidates are in the fray after as many as 10 candidates, including Congress' Manturam Pawar, withdrew their nominations in one hour on the last day of withdrawal of nominations Aug 30.
The contest is between the BJP's Bhojraj Nag and a virtually unknown Rupdhar Pudo of the Ambedkarite Party of India.
A total of 1.51 lakh persons were eligible to cast votes
Congress state president Bhupesh Baghel told IANS: "The BJP exercised money and muscle power to force Pawar to give up the contest.
"The entire local bureaucracy too helped the BJP to ensure that Congress does not contest. It was unethical on the part of the BJP and we took the matter to the Election Commission and also held a sit-in in Delhi to demand cancellation of the Antagarh by-poll."
However, BJP's state chief Dharamlal Kaushik rejected the Congress charges.
"The BJP wanted a contest in Antagarh but the Congress nominee ran away because of the internal rift within the party," he said.
Political analysts say that Pawar, known to be a die hard supporter of former chief minister Ajit Jogi, pulled out from the election to expose the leadership deficiencies of Baghel who has had a tense relationship with Jogi.
The wheelchair-bound Jogi had hit out at Baghel last week saying Pawar was fielded despite his reluctance to contest. The result will be announced Sep 16.