Mangrove forests are productive and biologically complex ecosystems that provide a wide range of environmental services and supply people with numerous goods. Growing in a variety of depths of salty water, mangrove forests play a significant role in supporting the coastal communities along Cambodia’s 440 kilometer-long coastline. However, mangrove forests in Cambodia have experienced great losses due to the impacts of intensive human activities. Although the human-driven mangrove losses in Cambodia have declined, the recent coverage change of mangrove forests needs to be evaluated for implementing effective regional ecological restoration programs. This study assessed the land cover change and fragmentation level of mangrove forests in Kampong Som Bay, Cambodia from 2015 to 2020. Using a combination of unsupervised and supervised classifications on Landsat 8 OLI/TIRS Level-2 satellite imageries, this study identified that 19,929 ha of mangrove forests remained unchanged, while 2,799 ha of mangrove forests were converted to other land cover types. The key driver of mangrove loss was the expansion of soil class, which could be explained by multiple human activities like rice agriculture and urban development. Based on the computation results of four landscape metrics, the mean patch size of mangrove increased but the shape of mangrove patches became more complex over time. To implement policies that conserve mangrove forests in Kampong Som Bay, it is essential to consider the deforestation occurring on the edge of mangrove patches.