Purpose Atezolizumab has been shown to be effective and safe in randomized trial in the first-line treatment of extensive-stage small cell lung cancer (SCLC). However, there are limited real-life data on atezolizumab. In this study, we aimed to determine the real-life efficacy and safety of atezolizumab combined with chemotherapy in the first-line treatment of extensive-stage SCLC. Methods This trial is a retrospective multicenter study of the Turkish Oncology Group, which included extensive-stage SCLC patients who received atezolizumab combined with chemotherapy in a first-line treatment. The characteristics of the patients, treatment and response rates, and PFS and OS are presented. Factors associated with PFS and OS were analyzed by univariate and multivariate analysis. Results A total of 213 patients at the 30 oncology centers were included. The median number of chemotherapy cycle was 5 (1-8) and atezolizumab cycle was 7 (1-32). After median 11.9 months of follow-up, median PFS and OS was 6.8 months (95%CI 5.7-7.8), and 11.9 months (95%CI 11-12.7), respectively. The ORR was 61.9%. ECOG-PS (p = 0.002) and number of metastatic sites (p = 0.001) were associated with PFS and pack-year of smoking (p = 0.05), while ECOG-PS (p = 0.03) and number of metastatic sites (p = 0.001) were associated with OS. Hematological side effects were common and toxicities were manageable. Conclusion This real-life data confirm the efficacy and safety of atezolizumab in combination with chemotherapy in first-line treatment of extensive-stage SCLC.