Research on the use of Flipgrid in the language classrooms has focused on its effects of online video-mediated communication tools, learners’ attitudes, and perceptions; nonetheless, not much research has recently been conducted about the influences of the Flipgrid app on EFL learners’ speaking anxiety. Therefore, this research aimed at investigating whether Flipgrid helps the EFL high school learners reduce their anxiety in learning English speaking and determine the learners’ attitudes towards its usages. The research followed a combination of a quasi-experimental method and a mixed-method with the participation of 60 EFL tenth-grade learners in a high school in the Mekong Delta. Three research instruments namely the modified Foreign Language Classroom Anxiety Scale (FLCAS), the questionnaire, and the interviews were employed in this study. The findings showed that there was a decrease in EFL high school learners’ level of anxiety in learning English speaking after experiencing Flipgrid. Moreover, the majority of the learners also showed their positive attitudes towards the use of Flipgrid in learning English speaking and expected that Flipgrid should be employed frequently to make learning English speaking become more motivating.