The advancement of digital technology has driven digitalization innovation in the field of education. Cultivating digital literacy of college students so as to enhance their online learning power is a new mission for higher education in the digital era. This study investigated the relationship between digital literacy and online learning power of EFL (English as a foreign language) undergraduates, and explored the role of perceived teacher support in it. The three scales concerning digital literacy, online learning power and perceived teacher support were used to conduct a questionnaire survey on 348 EFL undergraduates in a comprehensive university in Eastern China. The participants filled in the questionnaires and reported their survey responses. The results showed that digital literacy positively predicted online learning power, digital literacy was positively associated with perceived teacher support, and perceived teacher support was a positive predictor of online learning power. Perceived teacher support significantly mediated the relationship between digital literacy and online learning power. This study revealed that undergraduate digital literacy has an impact on online learning power through perceived teacher support, thus suggesting the importance of reinforcing teacher support, especially to enhance teachers' technology acceptance and beliefs.