Upper limb lymphedema (ULL) is a common and deliberating complication for breast cancer survivors (BCSs). Breast cancer survivors with ULL reported a wide range of symptoms. However, little is known about symptom patterns and interrelationships among them. This study was designed to explore symptom clusters and construct symptom networks of ULL-related symptoms among BCSs and to identify the core symptoms. This study is a secondary data analysis using datasets from three cross-sectional studies of BCSs in China. A total of 341 participants with maximum interlimb circumference ≥2 cm and complete responses in Part I of the Breast Cancer and Lymphedema Symptom Experience Index were included. Symptom clusters were identified through principal component analysis, and multiple linear regression analysis was employed to explore factors associated with severity of overall ULL-related symptoms. A contemporaneous network with 20 frequently reported symptoms were constructed after controlling for covariates. Three symptom clusters, including lymph stasis symptom cluster, nerve symptom cluster, and movement limitation symptom cluster, were identified. Postsurgery time, axillary lymph node dissection, and radiotherapy were associated with the severity of ULL-related symptoms. Tightness (rs = 1.379; rscov = 1.097), tingling (rs = 1.264; rscov = 0.925), and firmness (rs = 1.170; rscov = 0.923) were the most central symptoms in both networks with and without covariates. Breast cancer survivors with ULL experienced severe symptom burden. Tightness, tingling, and firmness were core symptoms of ULL among BCSs. Our findings demonstrated that the assessment and targeted intervention of specific core symptoms might help to relive effectively the burden of ULL-related symptom among BCSs.