Objective To understand the real experiences of self-management of cancer-related anorexia in patients undergoing chemotherapy after gastric cancer surgery, and to provide a reference for developing standardized self-management programs for cancer-related anorexia. Methods A descriptive qualitative research method was employed to conduct semi-structured in-depth interviews with 20 patients undergoing chemotherapy after gastric cancer surgery. Thematic analysis was performed using Nvivo 12 Plus software for coding, analysis, and theme refinement. Results The self-management experiences of cancer-related anorexia in patients after gastric cancer surgery were summarized into three main themes and nine sub-themes:lack of self-management knowledge (insufficient understanding of dietary self-management, insufficient understanding of dynamic nutritional support), related barriers to self-management (poor medication adherence, poor dietary adherence, heavy burden of self-perception), and positive attitudes and motivational behaviors toward self-management (patients′ expectations for appetite improvement, changes in dietary habits, sense of responsibility for personal health and family, enhanced self-efficacy). Conclusion Patients undergoing chemotherapy after gastric cancer surgery face numerous difficulties in self-managing cancer-related anorexia. Healthcare professionals should implement targeted nutritional education, pay attention to patients′ psychological changes, and explore new models for self-management of cancer-related anorexia suitable for these patients to enhance their self-management capabilities.