BackgroundBreast cancer‐related lymphedema (BCRL) is one of the common postoperative complications that severely affects the functions of the arm and quality of life. Since lymphedema is difficult to treat and prone to recurrence, early prevention of lymphedema is crucial.MethodsPatient diagnosed with breast cancer (N = 108) were randomized to the intervention (n = 52) or control group (n = 56). In the intervention group, patients were provided the lymphedema prevention program based on the theory of knowledge–attitude–practice during the perioperative period and the first three chemotherapy sessions (mainly includes health education, seminars, knowledge manuals, sports guidance, peer education, and WeChat group).The limb volume, handgrip strength, arm function, and quality of life were measured in all patients at the baseline, 9 weeks (T1), and 18 weeks (T2) after surgery.ResultsThe incidence of lymphedema in the Intervention group was numerically lower than in the control group after implementing the lymphedema prevention program, but the difference was not statistically significant (T1: 1.9% vs. 3.8%, p = 1.000; T2: 3.6% vs. 7.1%, p = 0.744). However, compared with the control group, the intervention group showed there was less deterioration in handgrip strength (T1 [t = −2.512, p < 0.05] and T2 [t = −2.538, p < 0.05]), improved postoperative upper limb dysfunction (T1 [t = 3.087, p < 0.05] and T2 [t = 5.399, p < 0.05]) and less deterioration in quality of life (T1 [p < 0.05] and T2 [p < 0.05]).ConclusionAlthough the investigated lymphedema prevention program improved arm function and quality of life, it did not reduce the incidence of lymphedema in postoperative breast cancer patients.