Background: Chronic diseases significantly impact global morbidity and mortality, affecting millions. Self-management interventions are crucial for improving patient health outcomes. This study explores the effects of self-management interventions on the quality of life (QOL), self-efficacy, depression, and anxiety of patients with chronic diseases. Methods: Relevant studies were searched from PubMed, EMBASE, and Web of Science. Two reviewers independently screened the literature, evaluated the risk of bias assessment, and extracted characteristics and outcomes among patients with chronic diseases. For each included study, we calculated the standardized mean difference (SMD) and 95% confidence interval (CI) of the main outcomes. When deemed feasible, the heterogeneity of the study was explored by meta-analysis and subgroup analysis. Results: Thirty-four studies involving a total of 7603 patients with chronic diseases were included. Self-management interventions significantly improved quality of life (Higher-better QOL and Lower-better QOL), self-efficacy, and reduced depression symptoms compared to usual care (95%CI 0.01 to 0.15, p = 0.03; 95%CI −0.49 to −0.08, p = 0.006; 95%CI 0.19 to 0.62, p < 0.001; 95%CI −0.23 to −0.07, p < 0.001). However, no significant effect was found for anxiety (95%CI −0.18 to 0.03, p = 0.18). In the heterogeneity analysis, Lower-better QOL and self-efficacy were all higher than 50% (I2 = 80%, 87%). After the subgroup analysis, the heterogeneity of Lower-better QOL and self-efficacy was less than 50% (I2 = 0%, 16.1%). Subgroup analyses revealed that studies with mean age greater than 60 years old and follow-up times greater than 6 months were more effective in improving patients’ Lower-better QOL (p = 0.03, p = 0.004), whereas follow-up times less than 6 months were better at reducing patients’ anxiety symptoms (p = 0.03). Conclusions: Self-management interventions are more effective than routine care in managing chronic diseases, significantly improving patients’ quality of life, self-efficacy, and reducing depressive symptoms, but they did not show significant improvements in anxiety symptoms. Overall, self-management interventions for chronic diseases can help patients adapt to the changes brought about by the disease and self-manage diseases to prevent disease progression.