Kierkgaard began skating at age three. She initially competed as a single skater in Denmark. She was a two-time Danish junior national champion and was the 2000 Danish national champion. Her 7th-place finish at the 2000 European Figure Skating Championships set a record as being the highest placement for a Danish lady at any ISU Figure Skating Championships, and was the first top-ten finish for a Danish lady since Ester Bornstein placed 8th at the 1934 European Championships.