Wozniacki is the daughter of Polish immigrants, Piotr and Anna Wozniacki. Her mother played on the Polish women's national volleyball team, and her father played professional football. The couple moved to Denmark when Piotr signed for the Danish football club Boldklubben 1909. Wozniacki's older brother Patrik is a professional footballer for Hvidovre IF in Denmark. Her best friend is her fellow Danish tennis player Malou Ejdesgaard, her doubles partner in some WTA tournaments. They are trying to gain entry to the 2012 Summer Olympics in doubles.
When asked in 2008 by Teen Vogue magazine what sports beside tennis she liked to play, Wozniacki said "I like handball, soccer, swimming, playing the piano, and all kinds of different things."
On 20 December 2010, she signed a three-year deal to endorse Turkish Airlines' business class service.Wozniacki is a supporter of Liverpool Football Club.
2010 tennis upskirt