Objective To explore the effect of WeChat-based multimodal nursing on self-care ability and scar aesthetic appearance in patients undergoing oncoplastic breast-conserving surgery (OBCS). Methods A total of 76 patients with OBCS admitted to Hejian Hospital of Traditional Chinese Medicine from January 2023 to December 2025 were selected as the research subjects. According to the random number table method, they were divided into the control group and the experimental group, with 38 patients in each group. The control group was given conventional high-quality nursing, and the experimental group was given WeChat-based multimodal nursing intervention on the basis of the control group. The self-care ability, scar aesthetic appearance and cosmetic effect were compared between the two groups. Results After 12 weeks of intervention, the VSS score of the experimental group was lower than that of the control group (P<0.05). After 12 weeks of intervention, the ESCA scores of the experimental group were higher than those of the control group (P<0.05). The excellent and good rate of cosmetic effect in the experimental group (94.74%) was higher than that in the control group (78.95%) (P<0.05). Conclusion WeChat-based multimodal nursing can effectively improve the self-care ability of OBCS patients, optimize scar appearance, and enhance overall cosmetic effect.