The 4-year-old collided with the vehicle at 11.45am this morning. Police rushed to the scene on the A30 in Hook, close to St John's church.
Hampshire and Isle of Wight Constabulary said: “The pedestrian, a 4-year-old girl, has been taken to hospital with serious injuries.
"Her family are aware and are with her. The road was closed in both directions while emergency services attended, but has now fully reopened.
"Officers investigating the circumstances of the collision would like to hear from anyone who was in the area at the time and saw what happened. We are particularly keen to hear from anyone with dash cam footage capturing the collision or the moments leading up to it.”
Anyone with information has been urged to call 101, quoting the incident number #0851 of today’s date. People can also submit information via the police website.