Natalie James said her daughter had been traumatised by the accident at a packed Brunswick Park in Wednesbury when a stray rocket veered into the 12,000-strong crowd and struck her.
She claimed seven-year-old Kacey-Lou had been left with a fear of fireworks.
The family had been leaving the Sandwell Council-run display shortly after 8pm when 'chaos' broke out.
Mrs James, aged 33, said they were around 100 yards from where the fireworks were being launched at the time
"It happened so quickly," she said. "We were leaving when this firework just shot out. I felt it skim my leg before it hit my daughter's.
"She was hysterical, then everyone started pushing and grabbing their kids, trying to get out. it was chaos. I was trying to protect Kacey from people kicking her as they were running.
"Some wardens came over and treated her. They cut through her leggings to get to the injury. Her leg was all red and swollen and she could barely walk. I had to carry her in the end."
The mother-of-three, of Village Walk, Wednesbury, has since taken her daughter to the doctor's surgery to have the injury checked and been told the youngster will make a full recovery.
But Mrs James said: "It was more traumatising than anything for a child of her age.
"We were in a shop that sold fireworks on Saturday and Kasey was hiding behind me because she though the fireworks might go off. I told her they had to be lit first but it didn't seem to reassure her."
Kasey-Lou's father, 34-year-old security guard Andy James, has sought legal advice over the matter with a view to suing Sandwell Council.
Mrs James said: "It's a shame because we've been to the display every year and it's been a great event. We only live round the corner, the kids have loved it, and the council put it on free of charge.
"But it was just shocking that this could happen at a public event."
A 43-year-old local man and two other people were also hurt in the incident.