Katalin Kovács started canoeing with her sisters and first competed for Budapesti Spartacus SC. She won her first medals at the 1993 European Junior Championships with silver in K-2 500 as well as in K-4 500 and became a member of the national team in 1995. In 1996 she was already nominated as a reserve for the Atlanta Olympics and in 1997, after changing to Újpesti TE, won her first medals on the senior level with two silvers at the European Championships as well as one silver at the World Championships. She won her first World title with gold in the 1998 K-4 200 metres. Her first Olympic medals came in 2000 when she won two silver medals. The following years she won nine gold medals at the 2001, 2002, and 2003 World Championships and for the 2004 Olympics she paired with Natasa Janics. This partnership resulted in Kovács’ first Olympic gold medal when they won the K-2 500 metres.
At the next two World Championships Kovács and Janics won three gold medals in 2005 and six gold medals in 2006, all in K-2 or K-4 events. At the 2006 European Championships they also won six golds in K-2 and K-4 events, in the 200 m, 500 m, and 1000 m. They did not compete together at the 2007 Worlds – nevertheless Kovács also won two gold and two silver – but paired again for the 2008 Olympics. In Beijing they successfully defended their K-2 500 m title and were also members of the silver medal winning K-4 500 m team. At the following two Worlds Kovács won two K-1 titles in 2009 and, with Janics, two more golds in 2009 and 2010. When Janics took a break in 2011 due to pregnancy, Kovács paired with Danuta Kozák for the Worlds and again won two gold medals. In total Kovács has collected 31 gold, six silver, and three bronze medals at the World Championships and 26 golds and 17 silvers at the European Championships.