Background: The COVID-19 disease has a negative impact on the psychophysiological health of populations worldwide, including a decrease in overall physical performance and an increase in fatigue. Fatigue was one of the main symptoms reported by patients and persisted for several weeks after infection with COVID-19. Although the phenomenon of fatigue is still poorly understood, physical activity can be a supportive factor in combating feelings of fatigue and lack of energy. The purpose of this research was to assess the physical activity (PA) and fatigue levels of teachers in Poland and the United Kingdom in the first year after the COVID-19 pandemic. Material and Methods: The online research was carried out among 410 teachers from Poland and the United Kingdom. The PA level was assessed using the International Physical Activity Questionnaire (IPAQ). The level of fatigue was measured using the Modified Fatigue Impact Scale (MFIS). Results: Polish teachers, regardless of sex, are more physically active (the differences relate mainly to walking and moderate activity). When assessing the level of fatigue, there is a significant difference between men and women – the former indicate a higher degree of fatigue, with the difference between the sexes being particularly large in the Polish community. Quite clearly, there is an association between less activity (except walking) and more fatigue. All models show a statistically significant effect of total fatigue on total effort. Physical activity is not very strongly correlated with age but the level of fatigue increases with age. Conclusions: The problem of teacher fatigue is unfortunately widespread. They should be encouraged to engage in as much PA as possible during the day. When planning and targeting fatigue reduction campaigns, PA should be encouraged and variables such as age, sex should be taken into account.