In this original paper, a new electrochemical sensor for carbamazepine (CBZ) was developed. First, lanthanum nanorods (LaNRs) were synthesized by a simple microemulsion method. Then, a nanocomposite consist of lanthanum nanorods, multiwalled carbon nanotubes (MWCNTs), and nafion (LaNRs/MWCNTs/Nafion) was prepared and deposited at the surface of the carbon ionic liquid paste electrode (CILPE). X‐ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersion spectroscopy (EDS), and scanning electron microscopy (SEM) were used to characterize the structure of synthesized LaNRs and the surface morphology of the modified electrode. Also, electrochemical methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the performance of the proposed electrode. Under the optimal conditions, a linear relationship of the electrical signal versus the concentration of CBZ was obtained in the range from 0.06 μM to 20 μM with a detection limit (LOD) of 0.006 μM and quantification limit (LOQ) of 0.02 μM. Eventually, the fabricated sensor was satisfactorily applied for rapid and accurate determination of CBZ in real samples.