Since the advent of new technology for learning, innovative language instructors have been constantly seeking new pedagogy to match the potential of technology-enhanced instruction. While previous studies have supported the adoption of technologies to facilitate language teaching and learning, research into enhancing English as a foreign language (EFL) learners' oral proficiency by creating an online learning community in a flipped classroom remains insufficient. Therefore, the current study examined the impact of an online learning community in a flipped classroom, specifically via mobile platforms, on EFL learners' oral proficiency and student perceptions. Fifty English-majored sophomores enrolled in two oral training classes at a four-year comprehensive university in central Taiwan participated in this study. A mixed method was employed to analyze multiple sources of data, including pre- and post-tests on oral reading and comprehension questions, a "Community of Inquiry" (CoI) questionnaire, and semi-structured focus-group interviews. The results from multiple sources indicated that the online learning community not only facilitated meaningful and positive collaboration but also significantly improved the participants' oral proficiency, thus leading to more active engagement in highly interactive learning activities, such as storytelling, dialogue collaboration, class discussion, and group presentations.