The escalating misuse of ephedrine in sports doping and illicit drug synthesis underscores the critical need for advanced detection platforms. In this paper, we describe in detail the development of a highly sensitive and selective electrochemical sensor for ephedrine, based on a molecularly imprinted polymer (MIP) integrated with conductive multiwalled carbon nanotubes (MWCNTs) and a conductive polymer layer onto a glassy carbon electrode. The fabrication involved functionalizing MWCNTs to enhance dispersibility, followed by the in situ polymerization of an ephedrine-imprinted acrylamide and N,N’-methylenebisacrylamide matrix. Extensive material characterization, including SEM and TEM, confirmed the formation of a porous, interconnected composite film with MWCNTs uniformly embedded within the MIP, featuring a polymer coating of approximately 10 nm, which is crucial for creating accessible molecular recognition sites. Electrochemical assessments via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) verified significantly improved electron transfer kinetics and successful template imprinting, as evidenced by changes in redox behavior and charge transfer resistance. The sensor demonstrated exceptional analytical performance for ephedrine detection across a linear range of 0.05 to 50 µM, achieving an impressively low limit of detection (LOD) of 15 nM and a sensitivity of 26.03 μA/nM. It exhibited marked selectivity against structurally analogous interferents, notably pseudoephedrine (K = 5.6). The sensor’s practical viability was robustly established with recovery rates between 95.4 and 103.5% in spiked human serum and urine. This MIP-CNT-based electrochemical sensor presents a significant advancement for rapid, cost-effective, and reliable ephedrine monitoring in clinical diagnostics and forensic science.