The boy remained in hospital in a stable condition today following the crash on Tividale Road, Tipton, yesterday just after 5pm.
The crash involved just one vehicle. No arrests have been made but West Midlands Police are investigating the incident.
Tividale Road was closed to traffic following the crash with motorists warned to avoid the area.
A spokesman for West Midlands Police said on Sunday: "We were called to a collision on Tividale Road, Tipton just after 5pm yesterday.
"A six-year-old boy was taken to hospital with a serious leg injury where he remains in a stable condition."