Chronic post-thoracotomy pain is a debilitating condition after traumatic multiple rib fractures and surgery. We aimed to estimate the prevalence of chronic post-thoracotomy pain after traumatic multiple rib fractures in South Korea and explore factors associated with it. From October 2017 to June 2019, a cross-sectional survey of 100 adults, who had undergone thoracotomy due to traumatic fractures of two or more ribs 2 years to 3 months prior to the survey, was conducted in the regional trauma center in South Korea. In total, 80% and 65% patients reported any level and above moderate chronic pain, respectively. Quality of life was mostly below the normative value of the US general population. Forty-six percent patients had restrictive respiratory dysfunction, and 47% and 59% patients were classified as being at risk of above mild-level anxiety and depression, respectively. More than 70% of patients had a current opioid prescription. Multivariable logistic regression analysis showed weak evidence of association between acute, severe postoperative pain and chronic postsurgical pain (adjusted odds ratio 2.4, 95% confidence intervals 0.9 to 6.4). Collectively, chronic post-thoracotomy pain and associated incomplete recovery regarding respiratory, functional, and psychological outcomes were prevalent in patients with traumatic multiple rib fractures in South Korea.