Objective: Little is known regarding the effect of sleep duration and weekend catch-up sleep (WCUS), sleep time on weekends that exceeds sleep time on weekdays, on suicidal ideation among adolescents with asthma. We explored whether sleep factors were associated with suicidal ideation among adolescents with asthma. Hypothesis: Adolescents with asthma are likely to have shorter sleep duration and longer WCUS than those without asthma. Study Design: Secondary data analysis for cross-sectional, self-administered, online survey. Patients Selection: Adolescents participating in the annual Korean Youth Risk Behavior Web-based Surveys (KYRBS, completed from 2013 to 2017). Methodology: The KYRBS data were obtained from a stratified, multistage, clustered sample. Students responded prior diagnoses of asthma and sleep time. Associated factors for suicidal ideation were tested by logistic regression models. Results: Among 34,067 and 363,003 adolescents with and without asthma, respectively, adolescents with asthma had poorer sleep satisfaction (44.6% vs. 42.6%), slept less (sleep duration 6.59 ± 0.94 vs 7.29 ± 1.45 hr), and had longer WCUS (3.13 ± 0.01 vs 2.29 ± 0.01 hr) than did those without asthma. The odds ratio (OR) of suicidal ideation in those with short sleep duration (defined by ≤5h) was 1.37 (95% Confidence Interval [CI], 1.30–1.43). Notably, long WCUS (≥2hr) was significantly associated with a decreased risk of suicidal ideation (OR, 0.88 [95% CI, 0.86–0.93]). Conclusion: Although further research is needed to clarify this association, long WCUS, which is a compensatory phenomenon for insufficient weekday sleep, protects against suicidal ideation in adolescents with asthma.