Objective <p>There is limited research on the impact of surgery on the cancer-specific survival (CSS) of patients with malignant thymoma and concurrent or previous extrathymic malignancies (PMTEMs). This retrospective analysis evaluated the prognostic value of surgery in PMTEMs.</p> Methods <p>Data were sourced from the SEER database, encompassing PMTEMs aged 20–90 with confirmed diagnoses and comprehensive clinical information. Patients were categorized into surgical (<i>n</i> = 105) and nonsurgical (<i>n</i> = 25) groups. Propensity score matching (PSM) was employed to mitigate selection bias, resulting in well-balanced baseline characteristics between the groups. Kaplan–Meier curves and the log-rank test were used to investigate the prognostic value of surgery in PMTEMs.</p> Results <p>Using PSM, the matching of characteristics between the surgical and nonsurgical groups was well-balanced, ensuring the reliability of subsequent analyses. Pre-PSM, the CSS in the surgical group was significantly better than that in the nonsurgical group (<i>p</i> &lt;.001). Similarly, according to the post-PSM data, the CSS for PMTEMs in the surgical group remained superior to that in the nonsurgical group, which indicates that the survival advantage of the surgical group persisted after PSM (<i>p</i> =.030). Additionally, PMTEMs with smaller thymomas (≤ 5&#xa0;cm) had a significant advantage in CSS compared to those with larger thymomas (<i>p</i> = .046).</p> Conclusions <p>In conclusion, this study shows that surgery may significantly improve the survival rate of PMTEMs.</p>