Mesoscale convective systems (MCSs) occur frequently throughout the Asian monsoon region (AMR) and exhibit distinct spatial distribution patterns while often triggering extreme weather events, including heavy rainfall, hail and tornadoes. To assess the hazardous impacts of MCSs and enhance disaster warning and response strategies, this study develops a database of MCSs across AMR from 2001 to 2023 using half-hourly infrared brightness temperature data and further examines their influence on weather hazard based on observational data. Results show that MCSs contribute more than 50 % of total precipitation in most parts of the AMR, underscoring their dominant role in the regional water cycle. More than 70 % of heavy rainfall events (HREs) over land and 47 % of strong wind events (SWEs) in the Chinese mainland are associated with MCSs, indicating the major contribution of MCSs to hazardous weather. Furthermore, MCSs account for over 70 % of hail and tornadoes occurrences in China, highlighting their strong association with severe convective storms. Statistically significant increases in both MCS activity are observed in eastern China, while statistically significant decreases are noted from western China to the Bay of Bengal. Notably, in eastern China and its adjacent seas (ECAS), the conditional probabilities of HREs and SWEs given MCS occurrence have been increasing at average annual rates of 2.77 % and 3.11 %, respectively. Given the upward trends in MCS activity and probability of hazard occurrence given MCS presence in eastern China, strengthening preventive measures against weather-related disasters in this region is imperative.