Little research has been conducted on posttraumatic stress disorder (PTSD) comorbidity among older adults regarding the description of PTSD in the 11th version of the International Classification of Diseases (ICD-11). This study sought to provide evidence of a dimensional model of psychopathology using the ‘Hierarchical Taxonomy of Psychopathology’ (HiTOP) model as a theoretical framework to explain patterns of ICD-11 PTSD comorbidity. Distinct patterns of ICD-11 PTSD comorbidity among a nationally representative sample (n = 530) of adults aged 60 years and older from the United States were examined using latent class analysis (LCA). Covariates associated with comorbidity classes were assessed through multinomial logistic regression. ICD-11 PTSD was highly comorbid with other psychopathologies. LCA results favoured a two-class solution. Class 1 (71.7%) was characterised by moderate probabilities for major depressive disorder and alcohol use disorder; Class 2 (28.3%) was characterised by a moderate-high probability of general psychopathology and was associated with lower social support, spousal/partner physical abuse, and history of attempted suicide. PTSD was highly comorbid with other disorders among older adults. Distinct patterns of PTSD comorbidity exist among this cohort and these findings can aid clinicians and researchers in understanding and predicting maladaptive responses to trauma and associated psychopathology.