Purpose: The impact of affective variables in second language acquisition is extensively researched, specifically focusing on literal language achievements, however, only a few studies have explored how these variables can predict the performance of Korean learning bilingual adults in different language domains. This study examines how affective variables (motivation, linguistic confidence, and ego-resilience) predict language-based problem-solving skills in Korean learning bilingual adults residing in Korea. Methods: Participants were composed of 26 bilingual adults who were living in Korea during the time of data collection and were learning Korean as a second language (L2). Participants completed the survey including the Language Experience and Proficiency Questionnaire (LEAP-Q), questions on measuring affective variables (motivation, linguistic confidence, and ego-resilience), and three domains of language-based problem-solving skills (sentence comprehension, idiom comprehension, and reading comprehension). Results: Motivation showed positive significant correlations with ego-resilience and linguistic confidence. Three significant correlations were also examined among the performance of language-based problem-solving skills: sentence comprehension and idiom comprehension, sentence comprehension and reading comprehension, and reading comprehension and idiom comprehension. Among the three affective variables investigated, linguistic confidence and ego-resilience of bilingual adults significantly predicted the performance of all three language-based problem-solving skills. Conclusions: The linguistic confidence and ego-resilience are essential for bilingual adults to cope with the interference and stress caused by cultural and linguistic differences, which leads to an improvement of the second language learning in all three domains.