Background <p>Brain metastases (BM) are a common complication in non-small cell lung cancer (NSCLC), associated with poor prognosis and limited survival without treatment. Previous studies have demonstrated a synergistic effect between radiotherapy (RT) and immunotherapy in NSCLC. This study aims to evaluate the efficacy of combining RT, immunotherapy, and platinum-doublet chemotherapy in NSCLC patients with BM.</p> Methods <p>This study retrospectively analyzed three open-label, randomized phase III trials (IMpower130, IMpower131, and IMpower150). NSCLC patients with BM who received RT combined with immunotherapy and platinum-doublet chemotherapy (immuno-chemoRT) were compared to those treated with immunotherapy and chemotherapy alone (immuno-chemo). Propensity score matching (PSM) was applied to minimize baseline imbalances between cohorts. The primary endpoint was overall survival (OS), with progression-free survival (PFS) as the secondary endpoint.</p> Results <p>A total of 134 patients were included in the analysis (immuno-chemoRT: <i>n</i> = 60; immuno-chemo: <i>n</i> = 74). The immuno-chemoRT cohort demonstrated improved survival compared to the immuno-chemo cohort, with a median OS of 19.2 months versus 10.6 months (HR: 0.55, 95% CI: 0.35–0.86, <i>P</i> = 0.008) and median PFS of 7.1 months versus 5.59 months (HR = 0.54, 95% CI: 0.37–0.78, <i>P</i> = 0.001). After PSM (1:1), the immuno-chemoRT group maintaining longer median OS (18.7 vs. 11.8 months; HR: 0.49, 95% CI: 0.29–0.83, <i>P</i> = 0.007) and PFS (7.1 vs. 5.75 months; HR: 0.54, 95% CI: 0.37–0.78, <i>P</i> = 0.015).</p> Conclusions <p>Our analysis suggests that immuno-chemoRT prolongs the OS and PFS of NSCLC patients with BM.</p>