Radek Stepanek has won 17 doubles titles. His rise in singles began in 2004 when, after starting from the qualifiers, he reached the final at the Paris Bercy Master Series, losing in three sets against Marat Safin. His first title was won in Rotterdam in 2006 by beating the Belgian Christophe Rochus in the final.
The same year he reached the final at the ATP Masters Series in Hamburg, where he lost to Spaniard Tommy Robredo in three sets, and reached the quarterfinals at Wimbledon. In 2007 he won the Los Angeles tournament by beating the American James Blake in the final.
In 2008 he managed to reach the semifinals of the Master Series in Rome by beating world number one Roger Federer in the quarterfinals in just 2 sets, in the semifinal he retired against the Serbian world number 3 Novak Dokovic due to a stomach problem in the second set on the score of 6-0 1-0 in favor of the Serbian. On 18 November 2012, in the Davis Cup final against defending champions Spain, he gave the decisive point (3-2) for the Czech Republic to win the trophy, against the more popular Nicolás Almagro, in 4 sets in almost four hours of play.
Still in the Davis Cup, in the final against Novak Dokovic's Serbia, Stepanek gave the decisive point (3-2) on November 17, 2013 against Dusan Lajovic with a score of 6-3; 6-1; 6-1.
In November 2017 he was Novak Dokovic's coach for a period, supporting another tennis legend like Andre Agassi in his role. He was engaged to Martina Hingis and for a short time to Petra Kvitova. He later married Nicole Vaidisova, twice.