Humberside Police are investigating after they were alerted to an incident on Thursday at an address in Sproatley.
Officers believe the youngster sustained serious injuries after being shot with a pellet gun.
Detective Chief Inspector Mark Goulding said: “We’re investigating the circumstances of the tragic death of a six-year-old boy in Sproatley.
“We were called at 4pm yesterday following reports the boy had been seriously injured at an address in Church Lane.
“He was taken to Hull Royal Infirmary but sadly passed away.
“Initial indication is this is a pellet gun injury but still we’re investigating the circumstances and the investigation is at an early stage.
“Our thoughts are with his family, who are being supported by specialist officers and we request that they are given privacy at this very difficult time.”