This longitudinal study explores changes in self-efficacy and motivational beliefs for learners beginning to study via English-medium instruction (EMI) at a transnational university in China. Following first-year local Chinese students over their first semester of learning via EMI, the study focuses on changes in learner self-efficacy beliefs towards lecture listening alongside task value, intrinsic goal orientation, and extrinsic goal orientation. It draws upon questionnaire (N = 412) and interview data (n = 34) to show significant gains in student self-efficacy due to (1) enactive mastery experiences and (2) the development of strategies for mediating the impact of negative affect. A midterm drop in the strength of intrinsic goal orientations contrasted with a greater focus on extrinsic factors, indicating that as students transitioned to the EMI environment, short-term extrinsic factors were of greater importance. However, findings indicate a rebound in the importance of intrinsic factors due to stronger self-efficacy and self-appraisals of success in EMI study, indicating a relationship between efficacy beliefs and intrinsic value orientations. The results contribute to the currently limited research on learner motivation development during transition into EMI transnational higher education.