The Republic of Korea has experienced rapid economic growth alongside increasing concern for animal welfare. However, progress in improving farm animal welfare remains slow, particularly in slaughterhouses, which are recognized as critical points for animal welfare concerns due to numerous issues observed. Due to the impracticality of assessing all slaughterhouses nationwide, this study conducted a field survey of seven chicken slaughterhouses utilizing the widely adopted WQ® protocol. The evaluation criteria included crate density, rough handling, plumage loss and emaciation, panting or huddling, wing flapping, vocalization, leg fractures, and dead-on arrival (DOA). Given that broilers are transported in crates from farms to the stunning area, the relationship between crate density and these welfare indicators was analyzed. The significance level was set at <0.05. Revealed correlations between crate density and various health and welfare indicators, including rough handling, plumage loss and emaciation, crate height, panting or huddling, pen spacing, lairage temperature and humidity, wing flapping, vocalization, and DOA. This study represents a pioneering effort in the Korean poultry industry, marking the first development of a welfare standard for chicken slaughterhouses.