Cancer, recognized as a significant global public health concern and a leading cause of mortality, refers to a group of diseases characterized by uncontrolled and abnormal cell division in the body that can potentially spread via the bloodstream and lymphatic system to other organs. Chemotherapy is one of the most effective cancer treatments available, but side effects of chemotherapy drugs limit its therapeutic use. Therefore, monitoring anti-cancer drugs concentrations is necessary to improve efficacy and reduce side effects. In this paper, a simple, fast, and sensitive sensor based on a carbon paste electrode modified by a nanocomposite containing graphene oxide and metal organic framework-235 (MOF-235/GO/CPE) was prepared for electrochemical detection of the anticancer drug doxorubicin (DOX). By using cyclic voltammetry (CV), chronoamperometry, and differential pulse voltammetry (DPV) techniques in phosphate buffer solution (PBS) at pH 7.0 as a supporting electrolyte, an analytical method for the measurement of DOX was established. CV results show that the MOF-235/GO nanocomposite modified CPE has a considerable rise in anodic and cathodic peak current compared to the unmodified CPE and exhibits good activity for the electrochemical reaction of DOX. The constructed sensor displayed a good response with a detection limit (3Sb/m) of 0.005 μM and wide dynamic concentration range from 0.01 to 100.0 μM for DOX. Additionally, the use of this sensor for determination of DOX in the presence of dacarbazine (DCB) was explored. With 0.335 V spacing between the two peaks, the modified electrode demonstrated outstanding characteristics for the electrocatalytic oxidation of DOX and DCB. Also, the MOF-235/GO/CPE sensor showed good reproducibility and selectivity toward the DOX. Finally, the satisfactory recoveries and RSD values were obtained for the detection of DOX and DCB in real samples.