Refugees experience various kinds of trauma during the migration process, which can cause psychiatric problems such as posttraumatic stress disorder. However, in the process of overcoming traumatic experiences, they may also experience posttraumatic growth (PTG). This study examined the level of PTG and its associated factors among North Korean defectors, including posttraumatic stress symptoms (PTSS). In total, 212 North Korean defectors completed self-report questionnaires measuring PTG (PTG inventory), PTSS (Posttraumatic Stress Disorder Checklist, PCL-5), quality of life (WHOQOL-BREF), and various sociodemographic variables. Participants completed the survey online, from July 27 to August 4, 2020. Participants reported a moderate level of PTG scores (51.7 ± 15.4, range 0–80). To determine the impact of PTSS on PTG among North Korean defectors, we conducted a hierarchical multiple regression analysis. In the final model, several sociodemographic factors (years in South Korea, education in North Korea, religion, and employment status), overall quality of life (β = 0.321, p < 0.001), and PTSS (β = 0.162, p = 0.035) were positively associated with PTG, whereas living with family (β = − 0.1261, p = 0.040) and loneliness (β = − 0.401, p < 0.001) were negatively associated with PTG, accounting for 36.6% of the variance in PTG scores (p < 0.001). This is the first large-scale study describing the level of PTG and its associated factors among North Korean defectors residing in South Korea. Further, our study provides suggestions for future research in this area, and interventions for improving PTG among this group.