Christiansen made her Olympic debut at the 2012 Summer Olympics in London, joining teammates Maja Jager and Louise Laursen for Denmark's first appearance in the women's team event, as well as competing in the women's individual event. The preliminary ranking round, which determined the seedings for the subsequent elimination rounds, saw Christiansen rank seventh for the individual competition with 663 points from a maximum of 720, while Christiansen, Jager, and Laursen's combined score for the team event set a new Danish national record of 1,946 points to finish with the eighth seed. The trio defeated India in the first knock-out round to advance to the quarter-finals, where they were defeated by South Korea.