Jarošík started his club career in his native Czech Republic, winning six league titles in seven years with Sparta Prague.

He also won the Scottish Premier League with Celtic in 2006–07, while in his later career he returned to Russia with Krylia Sovetov, had a second spell at Sparta, and played in Spain for Real Zaragoza and Deportivo Alavés.

Born in Ústí nad Labem, then Czechoslovakia,[2] Jarošík began his career with Sparta Prague in his native Czech Republic.

On 10 August 2004, Jarošík scored the winning goal in a 2–1 home victory over Rangers in the UEFA Champions League third qualifying round first leg (3–2 aggregate).

[6] He made his debut two days later in a 3–1 home win over League Two team Scunthorpe United in the third round of the FA Cup, as a 68th-minute substitute for Didier Drogba.

[9] Jarošík was involved in a controversy in February 2005 when he came on as a substitute with a 15-line handwritten note from manager José Mourinho, for midfielder Tiago Mendes, in a game at Everton that Chelsea ended up winning 1–0.

[11] On 4 April 2006, Jarošík scored the only goal against Bolton at St Andrew's; his long-range strike past Jussi Jääskeläinen took Birmingham out of the relegation zone for the first time since October.

[14] On 19 June 2006, Jarošík left Chelsea and signed a three-year deal with Scottish Premier League champions Celtic for an undisclosed fee, rumoured to be around the £2 million mark.

[16] Competition from other midfielders such as Evander Sno, Aiden McGeady and Paul Hartley meant that first team opportunities were limited for Jarošík, but he still made several notable contributions to Celtic's success, including winning both the free kicks from which Shunsuke Nakamura scored in the two Champions League group stage matches against Manchester United[17] – the second put Celtic into the last 16.

[23] On 28 November, Jarošík scored Celtic's equaliser in another Champions League group stage match – this time against Shakhtar Donetsk – with a left-footed volley.

[26] At the end of his Krylia Sovetov contract in December 2009, Jarošík returned to Sparta Prague to train, before being informed by a Serbian agent of interest from La Liga club Real Zaragoza.

[31] Jarošík was sent off on 2 October 2010 in a 2–2 home draw with Sporting de Gijón, for fouling David Barral for a penalty that Diego Castro scored.