The Childhood Health and Asthma Management Program (CHAMP) is a behavioral family lifestyle intervention for youth with overweight or obesity (OV/OB) and asthma. This pilot, randomized controlled trial examined the feasibility, acceptability, and preliminary efficacy of CHAMP. A sample of 24 children (Mage = 8.67) with asthma and a BMI at the 85th percentile or higher and their caregivers participated in the trial. Families were recruited from local pediatrician offices and pediatric pulmonary and allergy clinics and randomized to CHAMP or a health education attention control condition. Children’s height, weight, lung function, asthma control, and asthma-related quality of life (QOL) were collected at baseline, postintervention, and 6-months posttreatment. Analysis of covariance and standardized mean differences were used to assess changes in outcome variables among participants attending >50% of sessions (n = 12). Families participating in CHAMP reported high satisfaction; however, there were a number of barriers to recruitment and regular session attendance. There were no statistically significant between-group differences at postintervention or long-term follow-up. From baseline to postintervention, there were small to large effect sizes favoring CHAMP for BMI z scores, asthma control, and measures of lung function. There were small to medium effect sizes favoring CHAMP at long-term follow-up for BMI z scores, asthma control, and asthma-related QOL. CHAMP had adequate acceptability in this trial. We did not find significant results favoring CHAMP compared with the control group, however, lessons learned provide important directions for modifications in anticipation of a larger trial.