Officers were called to a serious road traffic collision on Brett Street, near to the junction with Britannia Road, at around 5.30pm.
The 12-year-old, who had been crossing Brett Street when the incident happened, was airlifted to hospital with serious head injuries. He died this morning.
A spokesperson for Humberside Police said: "We have specialist officers who are supporting his family. We ask on their behalf to respect their privacy at this time.
"No-one has been arrested."
"If you saw what happened, please contact us quoting log 472 of 15/2/19."
Tributes have been placed at the scene of the tragedy throughout the day.