Objective: To explore the practical effectiveness of nursing intervention based on the theory of Gratitude Extension-Construction in improving the sense of hope in breast cancer patients. Methods: A total of 104 breast cancer patients treated in our hospital from January 2023 to May 2024 were included and divided into a control group (routine nursing, 52 cases) and an observation group (routine nursing + nursing based on the theory of Gratitude Extension-Construction) using a random number table method. The Benefit Finding Scale (BFS), Hope Level Scale (HHI), and Quality of Life Questionnaire-Core 30 (QLQ-C30) were used to compare and analyze the scores of the two groups before intervention, 3 months after intervention, and 6 months after intervention. Results: There was no statistically significant difference in BFS, HHI, and QLQ-C30 scores between the two groups before intervention (P > 0.05). Both BFS and HHI scores increased in the two groups at 3 and 6 months after intervention compared to before intervention (P < 0.05), and the observation group had better BFS and HHI scores compared to the control group (P < 0.05). Before intervention, there was no significant difference in QLQ-C30 scores between the two groups in all dimensions (P > 0.05). Data comparison at 6 months after intervention showed that the observation group had better scores in all dimensions of QLQ-C30 than the control group (P < 0.05). Conclusion: Nursing intervention based on the theory of Gratitude Extension-Construction can effectively improve the benefit-finding ability of postoperative breast cancer patients, enhance their level of hope, and improve their quality of life. It is worthy of promotion and application in clinical nursing.