The Steve Asmussen trainee rated kindly behind soft fractions and outgamed second-place finisher Sprung and third-place finisher Quiet Jungle in the stretch.
The five-year-old daughter of Langfuhr traveled 1 1/8 miles in 1:50.01, after establishing fractions of :50.15 and 1:14.08.
"Around the bottom of the turn, I had a ton of horse. I thought it was going to take a real horse to outsprint us," said McAleney after his third career Dance Smartly Stakes score. "Steve (Flint, assistant trainer) had told me that this filly was doing better than ever. I knew I could ride her with a ton of confidence."
Flint said The Niagara Queen, who finished fifth in the May 31 Nassau Stakes, entered the race at the peak of her form cycle.
"It was her third start after a layoff. That's usually a horse's best race," said Flint. "She had worked exceptionally well."
The Niagara Queen, who is now a five-time winner, increased her career earnings to $571,219.
The Elite Racing Company-owned mare is now a multiple stakes winner. She won last year's Flaming Page Stakes.
The Niagara Queen returned $12.70, $7, $3.80, combining with Sprung ($8.30, $4.30) for a $95.50 exactor. Quiet Jungle ($3) rounded out a triactor worth $281.90.