[1] On 20 December 1986, he made his debut as Mieczysław Walpurg in the drama "Madman and the Nun" by Stanisław Ignacy Witkiewicz, directed by Krzysztof Jasiński in Theater Scena STU in Kraków.

In 2002, Gnatowski, who had been struggling with obesity since an early age, wrote the book "Diet without sacrifices", promoting a healthy lifestyle, together with Michał Mularczyk.

[4][3] In 2009, he lent his voice to the main character of the radio soap opera Gotowy na wszystko ("Ready for Everything"), broadcast on summer vacation on RMF FM.

[5][6][3] In 2012, he was nominated for the Jan Machulski Polish Independent Cinema Award for his role in the etude Kiedy ranne wstają zorze ("When the morning arise auroras").

On 20 October 2020, during the COVID-19 pandemic, Gnatowski was admitted to the Józef Dietl Hospital of Kraków, Poland, due to pneumonia, and despite the efforts of the doctors, developed acute respiratory failure and cardiac arrest, resulting in his death on the same day.