It happened at round 4.50pm yesterday on Chapeltown Road, Chapeltown, at the junction with Reginald Terrace.
A police spokesman said: “A Vauxhall Corsa was travelling on Chapeltown Road, northbound, away from the city centre, when it collided with a child.
“The four-year-old boy suffered serious injures and was taken to Leeds General Infirmary and was sadly pronounced deceased.”
Four-year-old boy dies in serious collision in LeedsOfficers are appealing for information from anyone who may have witnessed the collision or saw the vehicle prior to the collision.
Meanwhile, CCTV footage of the collision is also being reviewed.
Gurcharan Dass, owner of Chapeltown Mini Market, said cameras at the shop on Chapeltown Road had captured the whole incident.
The footage shows the moment the boy was knocked down on the pedestrian crossing opposite the Reginald Centre.
It also shows emergency vehicles arriving at the scene within minutes.
Anyone with any information is asked to contact the Major Collision Enquiry Team via 101 quoting log number 1292 of 29/4.