Purpose: This cross-sectional study aimed to explore the factors that affect quality of life (QOL) in patients diagnosed with primary lung cancer. Methods: Data were collected from 129 patients with stages 1 to 3 primary lung cancer who had visited the outpatient oncology-hematology department of a university-affiliated hospital in Gyeonggi Province from January 2024 to March 2024. The data were then analyzed using descriptive statistics, an independent t-test, one-way ANOVA, Pearson's correlation coefficient, and hierarchical regression analysis using the SPSS 25.0 program. Results: The mean score of QOL in the participants was 74.62±19.84. A hierarchical regression analysis revealed that symptom experience (β=-0.29, p<.001), depression (β=-0.46, p<.001), social support (β=0.18, p=.003), and marital status (β=0.11, p=.047) significantly affected QOL among patients with primary lung cancer. The regression model explained 64% of the variation in QOL. Conclusion The results demonstrated that patients would benefit from the development and implementation of nursing interventions that focus on reducing symptoms and depression, as well as improving social support, in order to improve their QOL.