Background: This research is inspired by the challenges encountered in interpreter training, changes in learning needs in the technological era, the educational paradigm shift caused by the COVID-19 pandemic, the lack of studies on combining virtual reality (VR)_and mobile technologies, and literature gaps in the field of the incorporation of technology in interpreter education. Objectives: This research aims to develop a mobile-based VR application for bi-directional English-Chinese and Chinese-English interpreting learning named 'Virtual Interpreting Practice' (VIP) based on an interpreting competence model and to investigate its impact on students' self-rated language and interpreting proficiency levels as well as their declarative knowledge and operative skills as reflected in different interpreting modes (sight and consecutive) and language directions (English-Chinese and Chinese-English). The VIP app contains learning resources, including 13 learning modules covering both interpreting modes, practical topics and contexts, video lectures and demonstrations, fully immersive VR and non-VR practice, glossary lists, source texts, translated texts and an online feedback platform. Methods: Thirty-one native Chinese-speaking English as a second/foreign (ESL/EFL) undergraduate students used the app for self-directed learning. The data were collected by the pre-study and post-study questionnaires as well as the pre-test and post-test. Results and Conclusions: The results indicate that the use of VIP significantly raised the students' self-rated language and interpreting proficiency levels as well as their interpreting performance in both modes and language directions. While the students performed better in sight interpreting and Chinese-English interpreting, they achieved a significantly higher improvement rate in consecutive interpreting and English-Chinese interpreting.