Yamaguchi and Ballas beat out their fellow finalists Jason Taylor and Edyta Sliwinska for the honor in the show's Season 6 finale.
Yamaguchi, an Olympic gold medal-winning figure skater, is the first female celebrity to win the coveted mirror ball since Kelly Monaco did so in Season 1.
"This is just the icing on the cake," Yamaguchi said upon learning her fate. "I honestly from the bottom of my heart thank all of the fans out there and everyone involved with 'Dancing with the Stars' from the crew, hair and makeup. ... Everyone who has made this a dream experience."