Background: While Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitors have been shown to be effective in phase III randomized trials, the value of targeted therapies have been challenging to evaluate at the population level. We examined the impact of population-level EGFR testing and treatment on survival outcomes among metastatic Non-Small Cell Lung Cancer (NSCLC) patients. Methods: Real-world, population-level data were collected from all de novo metastatic non-squamous NSCLC patients in Alberta, Canada from 2004 to 2020. EGFR testing data were collected through Alberta Precision Laboratories using various text mining approaches. Differences in survival rates and overall survival (OS) pre (2004-2012) and post-initiation (post) (2013-2019) testing periods were evaluated using interrupted time series analyses. The impact of testing and subsequent treatment weas evaluated using multivariable Cox Proportional Hazards models. Results: In total, 4,578 metastatic NSCLC patients with a confirmed non-squamous cell carcinoma histology were diagnosed pre-EGFR testing and 4,457 patients were diagnosed post- EGFR testing (2013-2019). Among patients diagnosed in the pre-EGFR testing period, the 6-month, 1-year, and 2-year survival probabilities were 0.39 (95% CI: 0.38-0.41), 0.22 (95% CI: 0.21-0.23), and 0.09 (95% CI: 0.08-0.10), while the survival probabilities for patients diagnosed in the post- EGFR testing period were 0.45 (95% CI: 0.43-0.46), 0.29 (95% CI: 0.27-0.30), and 0.16 (95% CI: 0.15-0.17), respectively. After adjusting for baseline patient and clinical characteristics, OS in the post-EGFR period was significantly improved compared to the pre- EGFR period (HR: 0.81; 95% CI: 0.78-0.85). In the post-EGFR period, among patients who were treated with systemic therapy, those tested for an EGFR mutation had significantly greater survival than patients who were not tested HR of 0.81 (95% CI: 0.70-0.95). Conclusions: These results show the considerable impact of population-based molecular testing and subsequent targeted therapies on survival among advanced NSCLC patients. The estimates here can be used in future studies to evaluate the population-level cost-effectiveness of testing and treatment.