"Dark Horse" is a song by American singer Katy Perry from her fourth studio album, "Prism". The song features American rapper Juicy J. "Dark Horse" was originally released as a promotional single from "Prism". After its unexpected success, it was released as the album's third single on December 17, 2013. "Dark Horse" became Perry's ninth number-one single in the United States. It was also number one in Canada. The song reached number four in the United Kingdom.