ABSTRACT Objective The causes of the long-term persistence of symptoms after a severe acute respiratory syndrome coronavirus 2 infection (i.e., post-COVID syndrome) remain elusive. Although previous research identified demographic and medical risk factors for the development of post-COVID, the present prospective study is the first to investigate the role of psychological factors. Methods The interview and survey data of polymerase chain reaction–positive participants (n = 137; 70.8% female) were assessed in the acute, subacute (3 months after symptom onset), and chronic phases (6 months after symptom onset) of COVID. Results After controlling for medical (body mass index, disease score) and demographic factors (sex, age), psychosomatic symptom burden (measured by the Somatic Symptom Disorder—B Criteria Scale) predicted higher odds and magnitude of COVID-related symptom impairment in the post-COVID phases. Fear of COVID-related health consequences (measured by the Fear of COVID Scale) also predicted higher odds of reporting any COVID symptoms in the subacute and chronic phases, whereas it only predicted a higher magnitude of COVID-related symptom impairment in the subacute phase. In subsequent exploratory analyses, we found that other psychological factors were associated with an overall increase (i.e., chronic stress and depression) or decrease (i.e., trait positive affect) in the odds and magnitude of COVID-related symptom impairment. Conclusions We conclude that psychological factors can fuel or temper the experience in post-COVID syndrome, opening new possibilities for psychological interventions. Trial Registration The study protocol was preregistered in the Open Science Framework (https://osf.io/k9j7t).