Jaromír Zmrhal broke into the Slavia Prague first team in 2012, making his league debut on 4 August in a 2–2 Gambrinus liga away draw against Baník Ostrava.

He scored his first league goal three weeks later in a 5–0 home win against FC Zbrojovka Brno.

In the 2015–16 season, he scored the winning goal in the Slavia - Sparta derby on 27 September 2015 with a powerful long-range effort.

[citation needed] On 6 August 2019, Zmrhal signed a four-year contract with Italian club Brescia.

[2] On 1 February 2021, Zmrhal moved to Czech club Mladá Boleslav, on a loan deal until the end of the season.