Purpose Cancer-related fatigue (CRF) is a pervasive symptom experienced by cancer patients. Sarcopenia has been suggested as a treatment target of CRF. This study aims to assess the differences of CRF and biochemical markers among different stages of sarcopenia which remain poorly delineated. Methods A total of 187 patients were included in this cross-sectional study. Based on muscle mass (skeletal muscle index, SMI), muscle strength (handgrip strength), and physical performance (SARC-F score), patients were divided into four groups (non-sarcopenia, pre-sarcopenia, sarcopenia, and severe sarcopenia). Cancer-related fatigue was measured by the Brief Fatigue Inventory (BFI). Biochemical markers were measured by routine blood tests. Results The BFI score was significantly associated with sarcopenia stage (r=0.500; P<0.001). Cancer patients in severe sarcopenia group suffered from worse CRF than those in non-sarcopenia, pre-sarcopenia, and sarcopenia groups (P<0.001). In the multivariate linear regression model (R-2=0.542), CRF was significantly correlated with SARC-F score (standardized B=0.519; P<0.001) and high-sensitivity C-reactive protein (standardized B=0.389; P=0.004). Serum albumin and cholinesterase were statistically correlated with both sarcopenia stage and CRF. Conclusions The significantly increased occurrence and severity of CRF in cancer patients with sarcopenia suggest that sarcopenia may be a crucial target to improve the management of CRF. Circulating albumin and cholinesterase have the potential to predicting sarcopenia as biomarkers.