This study aimed to examine the effects of open-task-based performance on English speaking skills and the affective domain in elementary English education. The classes included activities such as list-making, song lyric modification, role-playing, and group collaboration tasks. Data for analysis were collected through pre- and post-speaking evaluations, questionnaires, self-evaluation sheets, and additional questionnaires. The findings indicated that open-task-based language performance improved learners’ speaking abilities and enhanced their confidence, particularly in the affective domain. Moreover, the learners perceived task-based instruction as beneficial in improving their English speaking proficiency, with collaboration among group members identified as the most important factor in completing the tasks. Based on these results, it is recommended that, to effectively implement task-based language teaching in elementary English education, various language-integrated tasks with low cognitive load should be applied, along with efforts to promote the generalization of this approach.