Information regarding the age of amphibians is essential for species management, particularly with respect to invasive alien species. American bullfrog (Aquarana [Lithobates] catesbeianus) is a representative invasive alien species that are affecting ecosystems, but information on their age and growth rates is lacking. This study aimed to estimate the age and growth curve of A. catesbeianus in South Korea. A total of 49 individuals of varying sizes and sexes were collected from 10 different sites between 2019 and 2023. All individuals measured the snout-vent length (SVL) and estimated their age via skeletochronology. The analysis revealed distinct lines of arrested growth (LAGs) in bone cross-sections, allowing for accurate age estimation. The age of males was estimated to be 1- 5 years, females 0 - 4 years, and juveniles 0 - 2 years. No significant differences in age and SVL were found between sexes; however, a significant difference was observed between adults and juveniles. Given the limited sample size, the growth curve was estimated using only male individuals, revealing rapid growth up to two years of age, followed by a deceleration in growth rate. The asymptotic size and growth rate of A. catesbeianus was significantly larger than that of native amphibians, it could pose a substantial threat to native amphibians. These findings highlight the need for early monitoring and population control measures to mitigate the ecological impact of this invasive species.