The youngster was crossing Westfield Road in the town, close to St Peter’s and Clifton School when the collision occurred.
A police spokeswoman said: “Police were called by the ambulance service at around 8.40am to a road traffic collision involving a three-year-old boy.
“He was in collision with a car whilst crossing the road with an adult.”
She said the car involved was a brown Ford Estate.
Wakefield MP Mary Creagh said she was saddened to hear of the incident, which comes a day before a Wakefield Council consultation on the future of school crossing patrols closes.
The council is considering charging schools and academies to cover the cost of the service.
It said budget cuts of more than £146m mean it can no longer provider crossing patrollers free of charge.
Ms Creagh said: “I am shocked to hear that a young child was hit by a car near St Peter’s and Clifton school in Horbury this morning. This incident has left a family, and a school, traumatised. My thoughts are with the boy’s family, and I hope he makes a full and speedy recovery.
“When it comes to our children it must always be safety first. I’m calling on Wakefield Council to reinstate a school crossing patroller outside Horbury St Peter’s and Clifton Primary School, and reconsider their proposals to cease funding for school crossing patrols across Wakefield district.”
The school crossing patrol consultation closes tomorrow.
People can have their say by emailing [email protected]
Any witnesses to this morning’s incident are asked to call police with information on 101.