Geotagged Twitter data can be used to study the behavior of urban residents as they move to different places suited for various activities. In this study, geotagged Twitter data were used to explore the spatiotemporal changes in activity patterns of Bangkok Metropolitan Region (BMR) residents before and during the COVID-19 pandemic. BMR-tagged tweets were collected for 6- month periods in 2019 (i.e. before the pandemic) and in 2021–2022 (i.e. during the pandemic), and different statistical analysis methods were applied to extract temporal patterns and spatial distributions of activities. Both the temporal patterns and spatial distributions of activities showed changes between the two periods. The results showed that residents modified their behavior according to the circumstances and demonstrated that geotagged data can be used in urban studies to understand changes in residents’ behavior and identify the new normal.