The World Health Organization (WHO) released the WHO 2020 guidelines on physical activity and sedentary behaviour in November 2020. Compared with the 2010 WHO guidelines, this guideline has incorporated more extensive medical evidence and made targeted recommendations for special populations. The main content includes physical activity and sedentary behaviour advice for children and adolescents, adults, older adults, pregnant and postpartum women, people with chronic conditions, and disability. This review will interpret the 2020 WHO guidelines in detail.