Wilson said her daughter left at 3:40 p.m. for the party, which was just a few blocks away.
"She walked over to the couch and said, 'I love you,' and 'I'll be home by 7,' and she walked out the door and that was it," Wilson said. "She had been talking about the party. She was really looking forward to it."
The eight-block area Kayleah would have crossed to get to the party is well-populated and safe, according to authorities.
Wilson also said that she had no concern about letting her daughter walk alone and that the neighborhood is not dangerous.
"We all walk everywhere, we don't even have a car," she said. "It's not a bad neighborhood."
Wilson described her daughter as "loving" and "trusting," and said that she has always been well-behaved.
Other than that, Wilson said her daughter was a typical preteen who had a crush on one of the singers from the folk band Celtic Thunder.
On the morning of the day she disappeared, Wilson said her daughter had gone to church with her and had been happy during a lunch at a local restaurant with her grandmother.
ABC News' Clayton Sandell contributed to this report.