Joó won the 2010 European Championships in the -78 kg event, and regained her title in 2012. Since then, she has won three bronze medals in 2013, 2014 and 2017. As a junior, she had won bronze medals at the world junior championships in 2008 and 2009, in the 70 kg division. At European level, she won the European junior title at -70 kg in 2008 and 2009, having won the bronze medal in 2007 in the -63 kg division. She also won four European under-23 titles.