She made it clear that she intends to claim the show's mirrorball trophy.
"I haven't worked this hard for this long not to win this thing," she said Monday. "That trophy is mine."
The singer scored 87 out of 90 points for her three dances with professional partner Dmitry Chaplin. The pair was perfect on their paso doble and bested their fellow finalists with a perfect score during the megamix challenge, which saw them dancing side-by-side with Donny Osmond and Kelly Osbourne. Mya's "Hairspray"-themed freestyle dance didn't dazzle the judges, who gave it 27 out of 30 points.
"I was expecting something a little bit more spectacular," judge Bruno Tonioli said.
Osmond finished in second place with 85 out of 90 points. He and professional partner Kym Johnson earned a perfect score of 30 for their Broadway-inspired freestyle routine, which head judge Len Goodman called "an absolute show-stopper." The couple collected 27 points for their cha-cha and 28 during the megamix challenge.
Despite the second-place finish, Osmond said he still wants to become the "Dancing" champ.
"I want to win this mirrorball so badly," he said Monday. "Because if you had a sister named Marie and she was going to rub it in your face your whole life, you'd want to win, too."
A slim and smiling Kelly Osbourne finished third with 76 points out of 90. She and professional partner Louis Van Amstel collected 26 points each for their Argentine tango and megamix performance. The couple's glittery freestyle dance to the '70s classic "I Will Survive" earned 24 points - along with glowing praise from the judges.
"One thing is for sure," Tonioli said. "You never looked more beautiful than tonight."
Osbourne said she exceeded her own expectations on the ABC show.
"I didn't think that I really could do it, but this was my opportunity to show people that I have grown up," the reality star said Monday. "Every single dance we've done so far in this competition has been such a learning process and an adventure for me. I never thought we were going to get this far, but I'm so glad we did."
Each will perform again on Tuesday's episode, when a new "Dancing" champ will be crowned.