After competing in youth competitions through the 2000s, in 2007 Killman was named to her first National Team at the mere age of 16. In 2009 Killman found success at the United States National Championships, finishing third in the solo competition, second in the duet competition, and first in the team competition. Shortly before the 2011 Pan American Games in Guadalajara, Mexico, she was partnered with Mariya Koroleva to compete as a duet. At those games, Killman and Koroleva won a silver medal in the duet competition, and were part of the United States team that won a silver in the team competition as well. The pair qualified for the women's duet at the 2012 Summer Olympics in London, and due to the failure of the United States to qualify for the team event, they were the only American women to compete in synchronized swimming at those games.