Owned by Padua Stables and trained by Steve Asmussen, Juliet's Spirit notched her second consecutive stakes score, having won the five-furlong My Dear on June 30 at the Toronto oval.
As the field straightened for home, Juliet's Spirit seized command and braced for the challenge of a game After the Applause, gaining to the outside, and C Karma, squeezed back and checked at the turn, who finished second and third, respectively.
The final time over the Polytrack was 1:10.17.
"She epitomizes the term professional," said McAleney, who celebrated his first Ontario Debutante victory. "She came over today and she was smiling from ear to ear."
McAleney, who has been aboard the filly in all of her starts, noted Juliet's Spirit was more aggressive than usual in the early stages of the six-furlong race.
"She was a little more ambitious than she was last time," said McAleney. "She knew what she was here for. She did settle. When it was time to go, I let her go. I wound up going a little bit sooner than I wanted to because I didn't want to get into a wrestling match with her."
Juliet's Spirit launched her racing career on June 7, a neck nod at 4 ½ furlongs, courtesy of a late rally.
Prior to the Ontario Debutante, Juliet's Spirit triumphed by 2 ½ lengths in the My Dear, at odds of 7-1.
On Saturday, she was sent off as the 8-5 choice.
Juliet's Spirit paid $5.40, $3.50 and $2.50 across the board, combining with After the Applause ($7, $3.80) for a $44.40 exactor. C Karma ($4) finished third. The triactor paid $261.30. Dancingontheedge was scratched.