She drops last week's (ends18Apr14) chart-topper, Nobody to Love by dance music duo Sigma, to two on the new countdown, while Shift K3Y's Touch takes the third spot.
Kiesza tells OfficialCharts.com, "Being (number one) is the most amazing feeling ever. I just want to say thank you to everybody who's supported it."
Rounding out the top five is John Legend's All of Me and Aloe Blacc's The Man.
Meanwhile, on the albums chart, Paolo Nutini's new album Caustic Love grabs the number one spot with 2014's fastest-selling album, while The Vamps' Meet the Vamps ranks second on the countdown, and Paloma Faith's A Perfect Contradiction follows at number three.