The collision happened at around 5.20pm yesterday afternoon in Lythwood Road.
The boy had been a passenger on a bus moments before being involved in a collision with a blue Toyota Hi-Lux S estate.
He was taken to the Royal Shrewsbury Hospital with serious leg injuries.
A West Mercia Police spokesperson said today: “We are investigating the circumstances and appealing for witnesses to contact Shrewsbury police station on the 101 non-emergency number”.
No-one else was injured.