Background: This study aimed to examine the levels of fatigue, psychological distress, social support, uncertainty appraisal, and quality of life (QoL) in post-treatment patients with gynecological cancer and to evaluate how these factors influence their QoL. Methods: A cross-sectional correlation study was conducted with 150 women with gynecological cancer recruited through convenience sampling from the outpatient gynecology clinic of a tertiary hospital in Jeonju, South Korea. Data were collected using a structured questionnaire between 20 November 2024, and 10 January 2025. Statistical analyses included an independent t-test, analysis of variance, Pearson’s correlation, and multiple regression analysis. Results: The majority of participants were diagnosed with endometrial or ovarian cancer (74.0%). The mean QoL score was moderate to high (78.11 ± 14.20). QoL was positively correlated with higher fatigue scores (lower levels of fatigue) (r = 0.68, p < 0.001), greater social support (r = 0.58, p < 0.001), and higher opportunity appraisal (r = 0.34, p < 0.001), and negatively correlated with psychological distress (r = −0.59, p < 0.001) and danger appraisal (r = −0.28, p < 0.001). Multiple regression analysis identified fatigue (β = 0.45, p < 0.001) and social support (β = 0.36, p < 0.001) as significant predictors of QoL, accounting for 60.0% of the variance. Conclusions: These findings highlight the critical role of fatigue reduction and enhanced social support in improving the QoL of post-treatment patients with gynecological cancer. Targeted interventions addressing both physical and psychosocial factors are recommended for comprehensive survivorship care.