This study investigates the correlation between lifestyle and depressive tendencies among the middle-aged population in China, aiming to provide a policy basis for promoting mental health. Utilizing data from the China Health and Retirement Longitudinal Study (CHARLS) 2020, we employed the Ordinary Least Squares (OLS) regression model to conduct stepwise and stratified regression analyses to explore the heterogeneity in the association between lifestyle and depressive symptoms among middle-aged individuals in China. The findings indicate that middle-aged individuals who sleep 6 to 9 hours per night, work 4 to 5 days per week, and have a moderate annual income exhibit lower levels of depression. In contrast, those with poor self-rated health, infrequent internet use, lower levels of education, and non-marital status tend to have higher depressive tendencies. Additionally, gender and age were found to moderate these relationships. Therefore, the study advocates for and practices a healthy lifestyle, ensuring adequate sleep duration, implementing an optimized workweek system, improving the social security system, providing economic assistance and vocational retraining to increase personal annual income, and adhering to a holistic view of physical and mental health to provide precise care for middle-aged individuals, thereby enhancing the mental health level of the middle-aged population in China.