The coronavirus disease (COVID-19) outbreak has led to imposed movement restrictions and lockdowns to curb the spread of COVID-19 cases in the community. These lockdowns had greatly changed people’s daily lives, including physical activity and sedentary behaviour. The aim of this scoping review was to establish available evidence linked to physical activity (PA) and sedentary behaviour (SB) among adults in the Asia region during the COVID-19 outbreak. This scoping review was conducted using Arksey & O’Malley’s protocol with 132 studies included after full-text screening. Changes in PA were reported in 122 studies and SB in 50 studies. Most studies reported a reduction in the total level of PA and a hike in sedentary and screen time. This decrement in PA and increment in SB was related to poor mental health, body weight increase and complications in COVID-19 patients, while participants who maintained or improved their PA reported better health outcomes.