Jarkko Kalervo Nieminen (born 23 July 1981) is a Finnish former professional tennis player. His highest ranking of world No. 13, achieved in July 2006, is a Finnish record. He has won two ATP singles titles and five doubles titles in his career. His best performances in Grand Slam tournaments have been reaching the quarterfinals of the 2005 US Open, the 2006 Wimbledon Championships, and the 2008 Australian Open.
Arguably Finland's best player to date, Nieminen is also the first and so far only Finnish player to have won an ATP singles title and to have reached the quarterfinals of a Grand Slam singles event. He is also notable for winning the shortest recorded Masters Tour tennis match in Open Era history, defeating Bernard Tomic in just 28 minutes and 20 seconds in the first round of the 2014 Sony Open Tennis. He was ranked inside the Top 75 for 11 times in 14 years (2001 to 2014).
On 23 June 2015, he announced his retirement from professional tennis at the end of the season, playing 2015 Stockholm Open as his last event.
His wife, Anu Nieminen, is Finland's top-ranked badminton women's single player.
On April 2016, it was announced that Nieminen will compete in floorball in season 2016–2017 at Finnish Salibandyliiga representing SC Classic.