This study examined how Google Jamboard-based autonomous knowledge-sharing advanced language proficiency and motivation in an online intermediate--high EFL communication course. For one semester, 30 Korean first-year college students shared their learning experiences beyond the classroom, enhancing their English communication competence via a weekly Jamboard. The students speaking and perceived proficiencies and motivation changes were examined. Overall speaking proficiency increased, except for pronunciation. Students acquired the ability to selfstudy, but this was insufficient for oral practice because distance learning limited direct interactions. Perceived current proficiency increased, but imaginary proficiency and English importance did not. Their ease in using English in their daily life improved, and they felt the gap between the current and imaginary proficiencies decreased. The ideal L2 self increased, based on instrumentality and integrativeness. This finding indicates that students understood that they were undergoing the process of becoming fluent English speakers. Hence, well-organized self-directed activities can promote autonomous learning behavior to improve language proficiency and motivation.