The 12-year-old "Chandelier" dancer told ET that when she met the private pop star, there was an "instant connection."
"She's literally the sweetest person ever," she gushed. "I feel like I'm just so comfortable with her every time I'm with her. I never feel like, 'Oh my god, I'm hanging out with a celebrity.'"
"You would never guess she's a celebrity if you didn't actually know," Maddie continued. "She's the most humble person and so caring, and she like, cooks for me! She's such an amazing person."
Maddie admitted that since the first day the two met, they've been as tight as a knot, saying, "We just clicked!"
Sia inspires the young dancer, who hopes to break more into acting as she continues her career, to "stay humble."
"If I'm getting pushed to do something and I don't really enjoy it, I definitely let everyone know so I'm not doing something I'm not passionate about," Maddie said.
Sia is writing and directing a movie called Sister, which will star Maddie, who calls the role a "privilege" and "amazing."
And while Maddie says she's thankful for the recognition Dance Moms earned her, she "wants to move on to bigger and better things."
"I definitely want to be moving more into acting. Still keeping up my dancing, but also movies and scripted TV shows," Maddie shared.
And for advice on that, perhaps Maddie can confide in her "Elastic Heart" co-star, Shia LaBeouf, for whom she also had kind words.
"People think different of him, but he's literally such an amazing person too," Maddie said.
Meanwhile, Sia has been making her love of chandeliers known while moving into her new place!