Oral health is an indicator of patients' overall quality of life. Poor oral health among adolescents with asthma can affect their health in adulthood. This study researched the association between asthma and oral health symptoms in South Korean adolescents. Data from the 2020 Korea Youth Risk Behavior Web-based Survey were used. A total of 44,940 students participated in this study. The dependent variables were self-reported oral health symptoms. Asthma was the primary independent variable based on diagnosis in the past 12 months. The chi-squared test and multivariable logistic regression analysis were used. Students with asthma were associated with oral health symptoms, compared with those without asthma (boys, odds ratio (OR): 1.29, 95% confidence interval (CI) = 1.01-1.66; girls, OR: 1.94, 95% CI = 1.40-2.69). Poor health habits, such as low physical activity, higher sweetened beverage consumption, and fewer sleeping hours, were associated with oral health symptoms. Students who did not receive asthma treatment also had higher oral health symptoms (boys, OR: 1.29, 95% CI = 1.13-1.48, girls, OR: 1.34, 95% CI = 1.15-1.57). Students with absence due to asthma had a higher risk of oral health than those without asthma (boys, OR: 1.31, 95% CI = 1.17-1.46, girls OR: 1.28, 95% CI = 1.12-1.46). Students with asthma had a high risk of poor oral health among South Korean adolescents, suggesting more attention be given to regular dental check-ups and maintaining oral hygiene.