A BMW is understood to have been involved in a collision in High Street with another car, before striking his pram at around 4pm.
The young boy was being pushed along the pavement by family at the time and suffered serious injuries. He was rushed to hospital but nothing could be done to save him.
A relative suffered a shoulder injury but nobody else was injured.
The driver left the scene but a 34-year-old man was arrested in Bloxwich shortly afterwards. He has been taken into custody and will be questioned on suspicion of causing death by dangerous driving.
A section of the High Street has been closed to enable our collision investigation unit to carry out enquiries. The route is likely to remain blocked throughout the evening.
Sergeant Mark Crozier, from the unit, said: “A baby has tragically died and we’ll be doing all we can to support his family during this deeply devastating time.
“We’re in the process of speaking to witnesses and establishing the circumstances around this collision. I would ask anyone who was in the area, and has information which can assist our enquiries, to come forward.
“We understand the shock this will have caused but I would ask people not to speculate on what happened.”
We’re particularly keen to hear from anyone who was in the area and may have dash cam footage, either before or at the time of the collision.
Anyone with information can contact us via FL_COLLISION_INVEST@west-midlands.pnn.police.uk, via Live Chat or by calling 101.