Immigration is often discussed as a means to counteract population ageing. As the number of Asian countries experiencing population ageing continues to grow, we assess the potential impact of international migration on population ageing in Asia by combining replacement migration and prospective age concept, which accounts for differences in life expectancy. Using data from the UN’s World Population Prospects 2022, we estimate the potential replacement migration required to maintain the old-age dependency ratio and the size of the working-age population in eleven Asian countries over the period 2022–2050. Our results reveal large variation across countries, with the lowest replacement migration observed in countries where population ageing is already most advanced. In most countries, replacement migration exceeds observed net migration. Since increased immigration alone is unlikely to be the sole solution to population ageing, policymakers may consider a combination of different strategies to ensure future development in ageing Asian countries.