One of the mirrors shattered when Olivia Ward walked into it, cutting her legs and causing blood to pour out.
Her mother said there was so much blood "it looked like she had been bitten by a shark", adding she wants the maze to be closed.
The BBC has contacted Wheelgate Park in Nottinghamshire, but it has not commented.
The Health and Safety Executive is investigating to see if any laws have been breached, and whether the park could be prosecuted.
The nine-year-old's mother, Zoe Ward, believes the type of glass used is not suitable for a children's attraction.
"If it had been a little child running in there they would have got no eyes left; they would have had no face," she said.
"It was crazy, it was like she had been bitten by a shark or a dog.
"The cuts were so deep so she's got to rest up for the next week and try not to bend her legs.
"She needed about 20 stitches and they said she will be permanently scarred."
Olivia needed about 20 stitches to the wounds on her legs and is using crutches to walk.
Children are asked not to run through the maze, and Olivia's mother said she was definitely walking when it happened.
"I really don't know how it happened, unless it's just a weak piece of glass," she said.
"It's a maze so obviously you are going to walk into all sorts."
The park is required to report incidents like this to the HSE within 10 days. However, it has not done so yet.
The HSE started investigating when a member of the public contacted them.
A spokesman said: "We are aware of the incident and we have started an investigation."
A nine-year-old girl has been scarred for life after an accident in a maze made of mirrors at a theme park.