The SARS-CoV-2 virus pandemic has exerted enormous impacts on individuals’ lifestyle, economics and social life. The aim of the study was to assess the impact of the COVID-19 pandemic on health-promoting behaviors of a sample of the Polish population, including dietary supplementation, physical activity, eating habits, and the implementation of preventive vaccinations. Within the scope of a survey, data was collected from 1101 adult respondents residing in Poland (862 women and 239 men). An anonymous questionnaire prepared based on the scientific literature was used as a research tool. The survey was conducted during the second wave of COVID-19 using the CAWI (Computer—Assisted Web Interview) method by disseminating the questionnaire using selected social media. We found that, during the COVID-19 pandemic, the respondents were more likely to maintain healthy eating habits and use dietary supplementation; however, the majority engaged in physical activity less frequently and had a sedentary lifestyle. Most felt no need to undergo preventive influenza vaccinations. The COVID-19 pandemic significantly increased the health awareness of the analyzed group from the Polish population. However, the obtained results are not fully satisfactory; therefore, there is a need to promote a healthy lifestyle and pro-health behaviors as part of social campaigns.