Adverse childhood experiences (ACEs) and posttraumatic stress disorder (PTSD) are both associated with lower performances on executive function tasks. However, few researchers have evaluated ACEs, posttraumatic stress (PTS) symptoms, and executive function difficulties in conjunction. Using an online micropayment service, the current study assessed whether PTS symptoms mediated the relationship between ACEs and executive functions. In total, 83 participants (54.2% female, age:  = 28.86,  = 7.71) were administered the ACE questionnaire, PTSD Checklist for DSM-5 (PCL-5), and the Executive Function Index (EFI). A higher number of reported ACEs was related to greater PTS symptom severity ( = .40,  < .001) and worse self-rated executive functions ( = -.32,  = .002). Controlling for the number of reported ACEs, current PTS symptom severity was related to worse executive functions ( = -.45,  < .001). A bootstrapped 95% confidence interval (CI) indicated a significant indirect effect,  = -.18 (95% CI: -.30, -.08), by which current PTS symptoms mediated the relationship between the number of reported ACEs and executive functions. These results suggest that psychological interventions targeting PTS symptoms, in the context of a history of childhood trauma, may concurrently improve executive functions in adult populations.