Kyle Bastable, 11, who is also known as Joe by relatives, was hit by the DPD lorry close to the Shell garage at around 10pm yesterday.
Police were today trying to establish the events leading up to the tragedy.
The youngster was pronounced dead at the scene, off Wolverhampton Road.
Det Sgt Paul Hughes, from the force's Collision Investigation Unit, said: "A young boy has tragically lost his life and we are trying to establish the circumstances of what happened last night."
"This is a very busy junction and we are keen to hear from anybody who was in the area at the time and may have witnessed the collision - or saw the boy who was with a friend just beforehand.
"We have specially-trained officers supporting the boy's family at this extremely difficult time."
A DPD spokesman said: “We can confirm that a DPD vehicle was involved in a fatal accident at the Birchley Island roundabout in Oldbury last night, and that we are currently helping the emergency services with their investigation.
"Our deepest sympathy goes out to the family of the young boy involved.”
A West Midlands Ambulance Service spokesman said: “On arrival at the scene, crews discovered a young boy with serious injuries following the collision.
“Unfortunately, it quickly became apparent that nothing could be done to save him and he was confirmed deceased.
“A second boy was assessed at the scene before being left in the care of his parents.”
Aamir Suleman, the manager of the Shell garage off Birchley Island, told the Express & Star: "I was not on shift last night but I got a call saying there was an accident.
"I think the boy was crossing the road outside the garage when he got hit.
"The police came in for CCTV footage but our cameras only cover the pumps."