This quasi-experimental study examined the effects of speaking tasks on EFL learners’ speaking skills and Foreign Language Speaking Anxiety (FLSA) using a mobile application conducted outside the classroom. A total of sixty Iranian upper-intermediate level EFL students were divided into experimental and control groups to compare the effectiveness of speaking tasks using the Clubhouse application. Data were collected using the FLSA scale and the speaking pre-and post-test scores of the participants. The speaking proficiency of the participants was assessed based on the IELTS band descriptor, which included fluency and coherence, lexical resource, grammatical range and accuracy, and pronunciation. Utilizing one-way ANCOVA and Mann-Whitney U test, it was concluded that participation of the experimental group in speaking tasks at the Clubhouse improved their speaking proficiency and reduced their anxiety when speaking in the target language compared to traditional classes. The findings of the study call for the integration of synchronous mobile-based apps such as Clubhouse for out-of-class speaking tasks to improve EFL learners’ speaking skills and reduce their FLSA levels.