Police say the 17-year-old was babysitting when a mattress caught fire in a home in Trumann in January.
Three-month-old Blake Pierce died from smoke inhalation. His twin brother Drake and three-year-old brother Robert were also hurt from the smoke, but they survived.
Police say there were reports of illegal drug usage at the home.
The suspect is facing charges of negligent homicide and endangering the welfare of a minor.
His name is not being released because he is a juvenile. But police say he will prosecuted as an adult.