Upgrading firefighters’ life satisfaction can enhance their job skills, and contribute to their safety and that of the public. This study’s purpose was to identify general life satisfaction levels and national characteristics, including firefighters’ occupational issues in Korea and the US. The final sample sizes in this cross-sectional study were 1,523 for South Korea and 229 for the US. The findings were based on firefighters’ physical/mental health and satisfaction with occupational problems. To measure their life satisfaction, six dimensions were examined: social, spiritual, intellectual, emotional, physical, and occupational. The average satisfaction score of firefighters was 3.50 in Korea and 4.00 in the US. The US showed high satisfaction in most subitems. However, US firefighters showed low satisfaction in the physical context and Korean firefighters in the occupational context. Multiple regression analysis of the variables affecting firefighters’ life satisfaction showed that the occupational dimension was significant in both Korea and the US, and a similar analysis of demographic characteristics as independent variables showed that differences in satisfaction by gender were important in both countries. For Korea, the key variables were in the working hours section; for the US, in the specialty section. The results of this study should make it easier to identify and focus on the relevant areas of firefighters’ working lives in Korea and the US, thereby improving their life satisfaction.