Inflammation is thought to be a vital element in the etiology of cancer-related fatigue (CRF), and circulating blood cell parameters could be important markers of inflammatory response. However, the associations of several major blood cell counts and their derived inflammatory indices with CRF are not well described. The present study aimed to establish whether a relationship exists between the counts of three white blood cell (WBC) types, platelets, and CRF and investigate whether several systemic inflammatory indices were associated with CRF in patients with breast cancer (BC). A cross-sectional survey was conducted with a sample of 824 patients with BC undergoing chemotherapy. The cancer fatigue scale was administered to assess CRF. Hematological indicators, including neutrophils, lymphocytes, monocytes, and platelets, were retrieved from routine blood test. Network analyses were used to examine the associations among them. Among 824 participants, the mean score of CRF was (27 ± 10), ranging from 0 to 57. The results of network models indicated that physical fatigue was negatively linked to lymphocyte counts (weight = - 0.161), and affective fatigue was positively associated with neutrophil counts (weight = 0.070). Additionally, physical fatigue was positively linked to the platelet-to-lymphocyte ratio (PLR) (weight = 0.049). There were preliminary associations of counts of three WBC types, platelet counts, and systemic inflammatory indices, with distinct dimensions of CRF in patients with BC. Findings provide empirical support for the cellular basis of fatigue-associated inflammatory states.