Background: To determine the potential benefit of combining local and systemic therapy in stage IV non-small cell lung cancer (NSCLC). Methods: Data from stage IV NSCLC patients receiving systemic therapy alone, surgical resection and systemic therapy, or external beam radiation therapy/thermal ablation (EBRT/TA) and systemic therapy were acquired from the 2010-2015 National Cancer Database (NCDB). EBRT and TA patients were combined to enhance the power of the study. Overall survival (OS) was evaluated via multivariable Cox proportional hazards models. Comparison was made between EBRT/TA and systemic therapy alone utilizing 1:1 propensity matching analysis. A multivariable logistic regression model was used to determine variables predictive of lung cancer treatment. Significant variables (p < 0.05) were used to calculate the propensity score, and patients receiving EBRT/TA and systemic therapy were 1:1 matched using a greedy (nearest-neighbor) approach. Results: 46,964 patients from the NCDB database fulfilled inclusion criteria (surgical resection n = 1,235; EBRT/TA n = 12,456; systemic therapy alone n = 33,273.) Treatment differed across patient demographics and disease characteristics. Surgical resection demonstrated superior OS compared to EBRT/TA and systemic therapy alone, even after multivariable adjustment (compared to systemic therapy alone HR = 0.54, 95% CI: 0.50-0.58, p < 0.001; compared to EBRT/TA HR = 0.56, 95% CI: 0.52-0.60, p < 0.001). EBRT/TA treatment demonstrated superior survival compared to systemic therapy alone after accounting for confounders via propensity score matching (HR = 0.95, 95% CI: 0.93-0.98, p = 0.002). Interaction analyses indicated heterogeneous effectiveness of EBRT/TA according to patient demographics and cancer factors: the survival benefit of EBRT/TA over systemic therapy alone was especially pronounced in stage IV squamous cell carcinoma patients with limited nodal and metastatic disease (HR = 0.78, 95% CI: 0.71-0.85, p < 0.001 compared to systemic therapy alone; OS rates at 1-year = 50.9% vs. 42.4%; 2-years = 26.6% vs. 19.8%; 3-years = 17.2% vs. 10.1%). Conclusions: Stage IV NSCLC patients who received EBRT/TA or surgical resection in addition to systemic therapy demonstrated prolonged survival. EBRT/TA in combination with systemic therapy should be preferred in selected patients that are ineligible surgical candidates.