Due to the rapid rate of spread of the SARS-CoV-2 coronavirus, a number of restrictions have been introduced into public spaces, including those related to the operation of sports facilities, compounding the difficulty for athletes to conduct appropriate forms of training. The aim of this study was to review current scientific reports assessing the impact of the pandemic on the physical activity, mental state, and quality of life of professional athletes. Popular scientific databases—PubMed, Scopus, and Embase—were systematically searched from the beginning of the pandemic until 12 July 2021. According to the adopted criteria, 14 articles were included in the review. Ten of the qualified studies determined the impact of the pandemic on the physical activity of athletes. The authors of 11 papers assessed the mental state and quality of life of athletes during the pandemic. The studies showed negative effects of the pandemic: a decrease in overall physical fitness and number of days and hours of training, as well as an increase in the occurrence of negative emotions (stress, fatigue, and depression) and a decrease in sleep quality. Changes in physical activity had an impact on overall well-being ratings, which depended on the sex of the subjects. Women were more likely to experience negative emotions compared to men. The mental state of the athletes affected the quality of sleep. This review summarises the negative effects of the SARS-CoV-2 coronavirus pandemic on the physical and mental health of professional athletes.