Background: High antibiotic prescribing rates for adults with an asthma exacerbation have been reported in developed countries, but few studies have assessed the variation of antibiotic and adjunctive treatment in the routine care of children. Objective: We evaluated the trends in health resource utilization for children hospitalized for asthma exacerbation, ascertained the variations of practices across hospitals and geographic location, and classified these different patterns at hospital levels. Methods: Using data on Japanese children hospitalized for asthma exacerbation with no indication of bacterial infection during 2010–2018, we conducted a retrospective observational study to assess the trends in initial treatment patterns and their variations. Mixed-effect generalized linear models were used to investigate the treatment trends. Hierarchical cluster analyses were performed to classify the treatment variations across hospitals. Results: Overall, 54,981 children were eligible for the study. Proportions of antibiotic use decreased from 47.2% in 2010 to 26.9% in 2018. Similarly, utilization of antitussives, antihistamines, and methylxanthine showed decreasing trends over the period, whereas the use of mucolytics and ambroxol increased. These treatment variations were more considerable in hospital levels than in 47 prefecture levels. Hierarchical cluster analyses classified these patterns into 6 groups, mostly based on mediator release inhibitor, ambroxol, and antitussives. Conclusions: Wide variations in antibiotics and adjunctive treatments were observed across hospital levels. Our findings support the improvement in reducing inappropriate antibiotic use and highlight the need for comparative effectiveness research of the adjunctive treatments among children hospitalized for asthma.