Electronic apex locators (EALs) have transformed endodontic practice by providing a non-invasive, accurate method for determining working length (WL). Accurate WL measurement is crucial, as underestimation may leave residual infected tissue, compromising treatment success. This study aims to evaluate the influence of sodium hypochlorite (NaOCl) irrigant on WL measurements using an EAL at various stages of root canal procedures. Thirty-five adult patients requiring endodontic treatment on anterior or posterior teeth were recruited using simple random sampling. A total of 44 root canals were included. Pre-operative WL was measured on digital radiographs. After access opening, WL was recorded with a size 10/8 K-file using digital radiography. The canals were irrigated with 2.5% NaOCl, and WL was measured using an apex locator (E-Connect S, Eighteeth, China, 4th generation) under irrigated and dried conditions using paper points. WL was re-measured post-biomechanical preparation using the same apex locator. Statistical analysis was performed using GraphPadInStat software. Among 44 canals (16 anterior, 28 posterior), the mean pre-operative WL was 21.5 mm (SD 3.92) for anteriors and 19.2 mm (SD 2.57) for posteriors. A significant difference was observed between pre-operative WL and WL after access opening in molars (p=0.025). Additionally, WL measurements with and without NaOCl irrigant showed a significant difference in molars (p=0.006). NaOCl significantly affects apex locator accuracy, particularly in molars. Complete drying of canals before EAL use is recommended to improve measurement accuracy and optimize endodontic outcomes. The findings suggest that NaOCl significantly influences EAL-based WL measurements in molar teeth. Thorough canal drying prior to EAL use may improve measurement reliability.