The current study evaluated the effectiveness of delivering behavioral assessment and treatment to reduce challenging behavior shown by Korean children with ASD by using in-home telehealth from the U.S. The participants were five young children diagnosed with autism who lived in Korea and displayed challenging behavior. The children's mothers, who had no previous experience in functional analysis (FA) and functional communication training (FCT) procedures, implemented all procedures with coaching provided by a behavior consultant during assessment and treatment sessions via telehealth. The results of the current study showed that functional analyses conducted via telehealth from the U.S. to the children's homes in Korea were effective in identifying the function of challenging behavior for each participant. Furthermore, the results also showed that challenging behavior was reduced by 100% across all children by the end of treatment. These results suggest that telehealth can be an effective and efficient way to deliver behavior analytic services for underserved populations in countries like Korea.