The 2015 Formosa Fun Coast Water Park explosion was a devastating disaster in Taiwan, leaving 15 dead and 484 burn injured. The present study estimated the prevalence of probable PTSD, major depression (MDD), and significant posttraumatic growth (PTG) in burn survivors three years after the explosion. Potential predictors of PTSD and depressive symptoms and PTG (demographic, burn-related, and psychosocial variables) were examined. Participants were 125 young adult burn survivors. The mean age at the incident was 22.4 years (SD = 4.1) and 62.4% were female. The average total body surface area burned was 51.6% (SD = 19.2%). Three years after the explosion, 16.8% and 8.8% of the burn survivors met DSM-5 criteria of probable PTSD and MDD. Gender differences were observed in the prevalence of MDD but not PTSD. PTG was still highly prevalent, with 47.2%, 78.4%, and 84.0% of participants reporting significant PTG at the total scale, subscale, and item levels, respectively. Using hierarchical regression, psychosocial variables explained large amounts of variance in PTSD and depressive symptoms and PTG post-burn (△R2 = 0.411, 0.377, and 0.523) beyond that explained by demographic and burn-related variables. More avoidance and less approach coping predicted greater PTSD and/or depression symptoms post-burn. More approach coping and greater social support strongly predicted higher PTG post-burn. Rates of probable PTSD and MDD were relatively high in burn survivors, however, PTG was also highly prevalent. Coping styles and social support may play distinct roles in psychosocial adjustment after burn injury.