Vocabulary acquisition is a fundamental aspect of second language learning, and recent technological developments have provided new opportunities for enhancing vocabulary instruction. Among these technologies, Virtual Reality (VR) offers immersive and interactive learning environments that may influence learners’ cognitive processes. However, limited research has examined the combination of explicit vocabulary instruction and web-based VR while using objective measures of brain activity and cognitive load. Therefore, the present study investigates changes in brain wave activity and cognitive load experienced by English language learners during explicit vocabulary instruction in a pedagogically designed web-based VR environment. Specifically, the study examines whether exposure to explicit vocabulary instruction in VR is associated with changes in brain waves, including delta, theta, alpha, and beta activity, and explores the cognitive load experienced by learners during the instructional process. To address these objectives, Electroencephalography (EEG) is employed as an objective measure of learners’ brain activity, while cognitive load is assessed following exposure to the VR environment. By integrating VR, explicit vocabulary instruction, EEG, and cognitive load, the study aims to provide objective evidence concerning the cognitive and neural processes involved in technology-enhanced vocabulary learning. The findings are expected to contribute to applied linguistics and Computer-Assisted Language Learning by informing instructors, materials developers, and curriculum designers about the pedagogical and cognitive implications of web-based VR for vocabulary instruction.