Background and aim Handgrip strength (HGS) can be used to identify probable sarcopenia, by measuring maximum strength and/or through the average of three measurements. This study analyzed the agreement between maximum and mean HGS measurements in identifying probable sarcopenia in cancer patients. Methods Adult individuals of both sexes diagnosed with malignant neoplasm were evaluated. HGS (kg/f) was measured in both hands and nutritional status defined by the Patient-Generated Subjective Global Assessment (PG-SGA). Bland-Altman, Intraclass Correlation Coefficient (ICC), and Cronbach’s Alpha tests were applied to assess the agreement between measurements. Results One hundred forty-one patients aged 60.0 ± 14.2 years were evaluated. There was a predominance of elderly (57.4%), male (53.2%), and non-white (58.2%) individuals, with tumors located in the lower gastrointestinal tract (GIT) (36.9%) and with suspected or some degree of malnutrition (61.0%). For men, the Bland-Altman test showed a mean error of 1.37 (95% CI—1.03 to 3.80) for dominant HGS (DHGS) and 1.50 (95% CI—1.60 to 4.60) for non-dominant HGS (NDHGS), while for women the values were 1.34 (95% CI—0.27 to 2.95) and 1.14 (95% CI—1.10 to 3.39), respectively. The ICC showed excellent reproducibility (> 0.90) and the Cronbach’s Alpha was satisfactory (0.99). Conclusion Despite the satisfactory agreement observed between maximum and mean HGS values, in this study, individuals of both sexes with probable sarcopenia were better identified through mean values.