The seriously injured boy of Sarangagarh village was rushed to the local hospital and later shifted to Sishu Bhawan in Cuttack, police said.
The child's condition as stated to be stable.
The miscreant, however, could not take away the chain after committing the crime yesterday, they said.
In his FIR filed with the local police, the father of the victim Santosh Rout alleged that his son was playing in front of his house when the miscreant cut the chain around his neck in a bid to steal it.
But the kid cried in fear and hearing his screams his mother came out and saw the miscreant was cutting his chain. As she raised an alarm, the miscreant slit the child's neck and fled leaving the chain, the FIR said.