Sexual and gender minority adolescents face specific stressors associated with their minority status, leading to compromised socioemotional outcomes and sleep. Sleep patterns have, in turn, been found to predict socioemotional outcomes. As such, we aimed to investigate whether healthy sleep patterns prospectively predicted socioemotional outcomes, and whether associations varied as a function of sexual and gender minority status. We conducted a secondary data analysis among adolescents at age 14 to 17, from a nationally representative prospective cohort in the United Kingdom (N = 8923, mean age = 13.8), with 7021 cisgender heterosexual, 1801 sexual minority, and 101 gender minority adolescents. Indicators of socioemotional outcomes included self-esteem, emotional well-being, peer relationships, and relationship with parents. The results showed that gender minority adolescents reported the worst sleep patterns and socioemotional outcomes, followed by sexual minority and cisgender heterosexual adolescents. Results from multi-group path analyses showed that emotional well-being, self-esteem, and peer relationships at age 17 were prospectively predicted by sleep patterns and the associations were moderated by sexual and gender minority status. Influence of sleep patterns, particularly sleep initiation problems and frequent awakening, on socioemotional outcomes was greater among gender minority adolescents, when compared to cisgender heterosexual adolescents. In conclusion, positive socioemotional outcomes were predicted by healthy sleep patterns. The potential role of sleep health in optimizing socioemotional outcomes among sexual and gender minority adolescents might warrant further investigation in prevention or intervention studies.