Introduction: Personalized treatment helps one achieve optimal outcomes in patients with non-small cell lung cancer (NSCLC). Understanding patients’ survival prognoses in a palliative situation like intracerebral metastases is critical. A new survival score, the WBRT-30-NSCLC, was developed for patients with intracerebral metastases from NSCLC. Methods: Eight factors were investigated in 157 patients receiving 10 × 3 Gy of whole-brain radiotherapy (WBRT) including age, gender, Karnofsky performance score (KPS), interval from diagnosis of NSCLC to WBRT, pre-WBRT systemic treatment, primary tumor control, number of intracerebral metastases, and metastasis outside the brain. Factors significant (p < 0.05) or showing a trend (p < 0.08) on multivariate analysis were used for the WBRT-30-NSCLC. Patient scores were derived by adding factor scores (6-month survival rates divided by 10). WBRT-30-NSCLC was compared to other scores for intracerebral metastases from NSCLC. Results: On multivariate analysis, age (p = 0.005), KPS (p < 0.001), systemic treatment (p = 0.018), and metastasis outside the brain (p < 0.001) were significant; number of intracerebral metastases (p = 0.075) showed a trend. Four groups were designed (912, 1317, 1820, and 22 points) with 6-month survival rates of 3, 26, 65, and 100%. Positive predictive value (PPV) to predict death ≤ 6 months after WBRT was 97% (updated DS-GPA classification 86%, Rades-NSCLC 88%), and PPV to predict survival ≥ 6 months was 100% (updated DS-GPA 78%, Rades-NSCLC 74%). Conclusions: The WBRT-30-NSCLC appeared very precise in identifying patients with intracerebral metastases from NSCLC dying ≤ 6 months or surviving ≥ 6 months. It appeared more precise than previous scores and can support physicians developing personalized treatment regimens.