Rosie Marie Murphy, then four years old, was involved in a three-vehicle collision on January 4, 2016, on a country road in Barnsley.
She reportedly sustained life-changing injuries, which included spine and brain injuries.
In September 2020 her condition began to deteriorate and she died on October 12 the same year, aged nine.
PC Richard Thorley, of South Yorkshire Police, spoke at an inquest on Tuesday at Sheffield’s Medical-Legal Centre and said the youngster was not properly restrained and should have been in a booster seat.
Coroner Abigail Combes concluded her death was caused by a road traffic accident.