This paper presents an investigation into the integration of virtual reality (VR) tours in online English lessons tailored for adult learners. The study utilised a design-based research approach to evaluate the effectiveness of VR tours in this context. It specifically examined the responses of adult learners to this instructional strategy by collecting data through surveys, observation notes and interviews with four learners in Japan and five learners in France, most of whom completed 10 lessons over 4 months. The research findings highlight the effectiveness of VR tours in enhancing learner motivation. Additionally, they demonstrate that perceived learning outcomes are influenced not only by the immersive experience of spatial presence but also by the novelty of technological and scenery-related aspects within the VR environment, as well as factors related to lesson design and individual learner characteristics.