Abstract Objectives: Research examining the relationship between loneliness and Complex Posttraumatic Stress Disorder (CPTSD) is scarce, particularly among older adults. CPTSD includes the core symptoms of PTSD along with additional symptoms reflecting “disturbances in self‐organisation” (DSO). This study examined the cross‐sectional relationships between loneliness (emotional and social loneliness) and CPTSD symptoms (i.e., PTSD and DSO symptoms) in older adults. Methods: Structural equation modelling was used to examine these relationships in a nationally representative sample of US adults aged 60–70 years (n = 456). Results: Controlling for covariates, emotional loneliness was associated with PTSD (β = 0.31) and DSO (β = 0.57) symptoms whereas social loneliness was only associated with DSO symptoms (β = 0.25). The model explained 35.0% of the variance in PTSD symptoms and 71.3% in DSO symptoms. Conclusion: These findings have important implications for treating and understanding PTSD/CPTSD and their correlates among older adults.