Augmented Reality (AR) is an emerging educational technology that enhances learning by creating immersive and interactive experiences, effectively bridging the gap between abstract theoretical concepts and learner understanding. In Technical and Vocational Education and Training (TVET) institutions particularly within Building and Civil Engineering diploma programmes AR holds significant potential to modernize instructional approaches and improve comprehension in theoretical subjects such as Concrete Technology. This study investigates the impact of AR integration on trainees’ theoretical coursework in selected TVET institutions in Nairobi County. Although interest in AR's educational applications is growing, its use in resource-constrained technical training environments remains under-researched. Addressing this gap, the study examines how AR-based instruction can enhance mastery of theoretical content, offering trainees a more engaging and effective learning experience. The study targeted 73 trainers and 3,087 trainees across 10 selected institutions, from which 62 trainers and 354 trainees were selected using stratified simple random sampling. A Solomon Four-Group Experimental Design was employed to control for pre-test sensitization effects and ensure internal validity. Data collection followed a mixed-methods approach using structured questionnaires, interviews, and classroom observations. Quantitative data were analyzed through descriptive and inferential statistics in SPSS Version 23, including regression and correlation analyses; qualitative data were analyzed thematically. Findings indicate that AR significantly enhances trainees’ understanding and performance in theoretical coursework. Trainees exposed to AR demonstrated greater conceptual clarity and engagement, supported by interactive 3D models and visualizations. However, moderating factors such as trainer readiness and infrastructure availability influenced AR's effectiveness, offering essential insights for improving AR integration in technical education.