The girl, who has the mental capacity of an 8 year old, told her mother Tuesday night that her story wasn't true.
"I am horrified that she came up with such an elaborate lie," Krista Adams told KOMO News on Wednesday.
The girl claimed that a school bus picked her up at her regular stop in front of her driveway on Friday morning, but was later ordered off the bus when the driver realized she wasn't on the roster.
The girl's mother said her daughter has since admitted she missed the bus and tried to walk to school, but got lost. And when her grandfather found her on the street, "instead of telling the truth came up with this horrible, horrible lie," her mother said.
Her mom apologized for sounding the alarm over the story.
"I'm very sorry but in the end I would stand up for my child again -- I believed her," Adams said. "She had my whole family believing."
Marysville School District spokeswoman Jodi Runyon said the district was pleased to learn that the allegations were false and that the student is safe.
"The district takes student safety seriously and several hours were spent by school district and transportation staff to investigate these allegations," she said.