Asthma morbidity disproportionately impacts children from low-income and racial/ethnic minority communities. School-supervised asthma therapy improves asthma outcomes for up to 15 months for underrepresented minority children, but little is known about whether these benefits are sustained over time. We examined the frequency of emergency department (ED) visits and hospital admissions for 83 children enrolled in Asthma Link, a school nurse-supervised asthma therapy program serving predominantly underrepresented minority children. We compared outcomes between the year preceding enrollment and years one-four post-enrollment. Compared with the year prior to enrollment, asthma-related ED visits decreased by 67.9% at one year, 59.5% at two years, 70.2% at three years, and 50% at four years post-enrollment (all p-values < 0.005). There were also significant declines in mean numbers of total ED visits, asthma-related hospital admissions, and total hospital admissions. Our results indicate that school nurse-supervised asthma therapy could potentially mitigate racial/ethnic and socioeconomic inequities in childhood asthma.