The purpose of this study was to investigate the effects of adult English learners’ L2 selves on learning motivation for successful English learning. The results are as follows: First, the learning motivation of adult English learners showed differences according to English proficiency level. Goal-oriented and activity-oriented motivations did not show significant differences depending on proficiency level, whereas learning-oriented motivation showed statistically significant differences between the two levels. This indicates that learners' English proficiency has a meaningful effect on learning-oriented motivation in this study. Second, the L2 selves of adult English learners were found to influence all types of learning motivation. Both the ideal self and the ought-to self had significant effects on goal-oriented, activity-oriented, and learning-oriented motivations. Lastly, according to the results of this study, which examined the effects of adult English learners' L2 selves on learning motivation by English proficiency level, the ideal self and the ought-to self were found to have a positive effect on learning-oriented motivation after inputting English proficiency level as a control variable. It appears that the negative impact of the ought-to self in English learning did not emerge, as learners voluntarily chose to study English and were not evaluated by formal institutions. These findings prompt reflection on how English education in Korea remains excessively outcome-oriented, with performance often judged by test scores. If the goal of English learning is communication, then the ought-to self—an essential motivational factor—should not be considered a source of negative influence. Rather than relying on outcome-based evaluations that determine success or failure, assessments that emphasize the learning process and consider individual learner characteristics should be actively adopted in educational settings. Such an approach could enhance the positive impact of the ought-to self, a powerful motivator in second language acquisition.