Vocabulary is at the first rank among grammar and pronunciation components in assessing how well someone understands a language. As stated in some previous studies, the majority of EFL learners have encountered difficulty in vocabulary mastery. In response to the study, more significant efforts need to be implemented to assist EFL adult learners in mastering English vocabulary. The present study explored the EFL adult learner’s experiences in learning vocabulary by reading digital books based on Nation’s (2013) aspects of vocabulary knowledge. Moreover, it also investigates the impacts of learning vocabulary by reading digital books. The present study assisted the autobiographical narrative inquiry method and gathered the data through a diary and artifacts. The researcher as the reflectioner in this study was experienced in learning vocabulary by reading digital books. Furthermore, the thematic analysis was assisted in analyzing the data. The finding exposed that the EFL adult learner felt that reading digital books within a certain duration of time and a certain amount of digital books had impacted her vocabulary knowledge. Furthermore, reading digital books has influenced her motivation in learning vocabulary and other language skills. Therefore, teachers can utilize technology in learning activities that can have an impact on independent learning activities while inside and outside the classroom.