The promise of the ceasefire – to come into effect on 15 October – came days after a string of blasts blamed on the National Democratic Front of Bodoland left 53 people dead in various parts of the state.
"In response to the Assam chief minister's offer for a ceasefire, the National Democratic Front of Bodoland has decided to accept the offer for a period of six months effective October 15 to create a congenial atmosphere for talks," D.R. Nabla, president of the rebel group, said in a statement.
"All the commanders of the Bodoland army have been asked to stop hostilities against India," he added.
The outlawed National Democratic Front of Bodoland was formed in 1986 and has been fighting a guerrilla war to carve out an independent homeland for the Bodo tribe in Assam.
But Assam is home to many rebel groups fighting for divergent causes and the Bodo separatists group is just one of them.
Assam Chief Minister Tarun Gogoi gave a cautious response to the Bodo announcement.
"We shall have to wait and watch and see the genuineness of the offer. We shall respond in a day or two," he said.
The National Democratic Front of Bodoland claimed responsibility for at least four of the deadly attacks over the last weekend.
Nearly 10,000 people have died in insurgency related violence in the state over the past two decades.