Due to the spread of COVID-19, all face-to-face speaking courses were discontinued for a while, which inevitably impaired assessment results. E-portfolios are typically an appropriate evaluation technique for universities that implement fully synchronous online learning in pandemic situations. However, little is known about how this alternative assessment technique influences student speaking performance and self-efficacy. As a response, this study explored the impacts of e-portfolios on students' speaking performance and self-efficacy when studying from home, owing to the COVID-19 pandemic. A mixed-methods experimental design was used, with 55 university students (experimental = 28, control = 27) aged 18-20 years. Data were gathered via pre- and post-speaking tests, pre- and post-self-efficacy questionnaires, and an interview guide. The statistical analysis revealed that the experimental group outperformed the control group regarding speaking performance and self-efficacy. Furthermore, the interview findings indicated that the activities in e-portfolios were crucial for these improvements. This article suggests innovative approaches for teaching online speaking courses with e-portfolios.