Petr Kotlařík was born on 1 November 1998 in Jihlava and grew up in Brno, Czech Republic.

Kotlařík debuted on the Junior Grand Prix (JGP) series in October 2013, coached by Eva Horklová and Lucie Kratěnová in Brno and Prague.

[5] In March, he competed at the 2017 World Junior Championships in Taipei, Taiwan; he qualified to the free skate and finished 23rd overall.

He was coached by Florent Amodio in Hackensack, New Jersey, United States, and by Petr Starec in Brno, Czech Republic.

[6] Kotlařík is coached by Amodio in Vaujany and Paris (France), Hackensack (New Jersey, United States), and Brno (Czech Republic).