The study of blowfly (Diptera, Calliphoridae) biodiversity and distribution is crucial for forensic investigations involving cadavers. Abiotic and biotic factors, such as seasonality and habitat type, have significant impacts on blowfly populations. However, few forensic entomology studies have been conducted in South Korea, particularly the Gyeongsangnam-do region. To address this, in this study, an extensive year-long survey was conducted to analyze the compositions, habitat preferences, distribution, and seasonal abundance of forensically relevant blowflies in urban and forested habitats in Gyeongsangnam-do, utilizing mouse carcass-baited traps set for 48 h each month. A total of 3,478 adult blowflies were recorded, encompassing six genera and 14 species, with a noted absence of specimens during the winter months. The predominant species was Lucilia porphyrina, accounting for 37.1% of the total sample, followed by Chrysomya pinguis (27.5%), Lucilia sericata (7.6%), and Lucilia illustris (7.1%). The species composition was consistent across all surveyed regions; however, seasonal variation in species diversity was evident, with a peak in spring and decline in summer. Notably, certain species exhibited clear preferences for either urban (Calliphora calliphoroides and L. sericata) or forested habitats (L. porphyrina and Ch. pinguis). This pioneering study elucidates the diverse blowfly communities in Gyeongsangnam-do, highlighting significant seasonal and habitat-dependent variations.