PURPOSE There have been no previous longitudinal assessments of health-related quality of life (HRQoL) during treatment for pediatric Hodgkin lymphoma (HL). The addition of brentuximab vedotin (BV) to a multidrug chemotherapy backbone demonstrated superior efficacy to standard chemotherapy for patients with pediatric high-risk HL in the AHOD 1331 trial. However, the impact on HRQoL is unknown. PATIENTS AND METHODS After treatment random assignment, 268 participants older than 11 years were enrolled in a prespecified, longitudinal, patient-reported outcomes substudy. HRQoL was assessed using the seven-item Child Health Ratings Inventories (CHRIs)–Global scale before treatment (T1) and at cycle 2 (T2), cycle 5 (T3), and end of treatment (T4). A clinically meaningful increase in HRQoL was considered 7 points on the CHRIs-Global. Multivariable linear regression estimated associations between demographic/clinical variables and HRQoL at T1. Linear mixed models estimated changes in HRQoL across the treatment arm. RESULTS Participant characteristics were balanced by treatment arm. Ninety-three percent of participants completed the CHRIs at T1, 92% at T2, 89% at T3, and 77% at T4. At T1, female sex and fever ( P < .05) were each associated with worse HRQoL. By T2, participants in the BV arm experienced a statistically and clinically significant improvement in HRQoL (β = 7.3 [95% CI, 3.2 to 11.4]; P ≤ .001), which was greater than the change in the standard arm (difference in change β = 5.1 [95% CI, −0.2 to 10.3]; P = .057). The standard arm did not experience a statistically or clinically significant increase in HRQoL until T4 (β = 9.3 [95% CI, 4.7 to 11.5]; P < .001). CONCLUSION These data demonstrate successful collection of serial HRQoL from youth with high-risk pediatric HL and improvement in HRQoL over the course of initial therapy, sooner and to a greater extent in the group receiving the novel agent BV.