N-ethylpentylone (NEP), also known as ephylone, is a synthetic cathinone (SC) that has been banned worldwide since 2019 due to alarming cases of intoxication. However, preliminary identification of this drug is of interest in the forensic scenario. Here, a new forensic application using a lab-made screen-printed sensor with chemically deposited boron-doped diamond electrode (LM-SP/BDDE) for the detection of SCs is presented. We present, for the first time, the electrochemical behavior of NEP and its detection in forensic samples using a versatile, robust, low-cost, and simple sensor that requires a small sample volume (30 µL) for the analysis. NEP presented three irreversible and independent redox processes (O₁ at +0.88 V, R₁ at –1.3 V and R₂ at –1.45 V), and a dependent reduction R₃ at –1.6 V vs. Ag/AgCl. The proposed method for NEP detection on LM-SP/BDDE was optimized by adsorptive stripping differential pulse voltammetry (AdSDPV). The use of LM-SP/BDDE with AdSDPV provided a good stability of NEP electrochemical responses using the same electrode (n = 5), with RSD < 4.0% for all redox processes. Furthermore, wide linear ranges for NEP determination (1.0 – 100.0 µmol L ^{− 1}) with a low LOD (0.66 µmol L ^{− 1}) were obtained. Interference studies have been performed for common adulterants and other illicit drugs (semi-synthetics, amphetamines, and other SCs), and a highly selective response for NEP detection was observed. Therefore, LM-SP/BDDE combined with AdSDPV is an alternative tool for selective screening of NEP in on-site forensic analysis, providing rapid and simple preliminary identification.