The Congress has won 66 seats and is leading in two more in the 90-member Assembly, while the BJP has been relegated to a distant second spot, winning just 15 seats, according to the results available at 5.30 am on Wednesday.
The Mayawati-led Bahujan Samaj Party (BSP) has won two seats, while the Janata Congress Chhattisgarh of former chief minister Ajit Jogi has won five. The two parties fought the polls in an alliance.
After it became clear that the Congress was heading for a massive victory, Chief Minister Raman Singh submitted his resignation to the governor.
Singh told reporters Tuesday that he accepted the responsibility for the loss, refusing to pass the buck to the BJP's national leadership.
"The election was solely contested on a state agenda and it was not related to Delhi. We will sit with the party workers and analyze the defeat in detail.
"This will not reflect on the 2019 Lok Sabha election," he said.
In the 2013 Assembly polls, the BJP had won 49 seats, the Congress 39, while one seat each was bagged by the BSP and an Independent.