The major focus of the study was the impact of the COVID-19 pandemic on healthcare workers’ mental health. Nurses are the workers who were exposed to pandemic–related stress, being the most affected. The present cross-sectional study was focused on finding out the differences of the level of work-related stress and quality of life in nurses of the three Central European states, specifically the Czech Republic, the Slovak Republic, and Poland. A structured anonymous online questionnaire was created, and then the link was distributed to the target population through executives. Data analysis was performed by using the R programme–version 4.1.3. The study found that nurses from the Czech Republic achieved lower stress levels and had a higher quality of life than nurses from Poland and Slovakia.