To determine clinic-level and individual-level correlates of viral suppression among HIV-positive adolescents and young adult (AYA) aged 10-24 years receiving antiretroviral treatment (ART). Multilevel cross-sectional analysis using viral load data and facility surveys from HIV treatment programs throughout Kenya. We abstracted medical records of AYA in HIV care, analyzed the subset on ART for more than 6 months between January 2016 and December 2017, and collected information on services at each clinic. Multilevel logistic regression models were used to determine correlates of viral suppression at most recent assessment. In 99 HIV clinics, among 10 096 AYA on ART more than 6 months, 2683 (27%) had unsuppressed viral load at last test. Among 16% of clinics, more than 80% of AYA were virally suppressed. Clinic-level correlates of individual viral suppression included designated adolescent spaces aOR: 1.32, 95% CI (1.07-1.63) and faster viral load turnaround time aOR: 1.06 (95% CI 1.03-1.09). Adjusting for clinic-level factors, AYA aged 10-14 and 15-19 years had lower odds of viral suppression compared with AYA aged 20-24 years aOR: 0.61 (0.54-0.69) and 0.59 (0.52-0.67, respectively. Compared with female patients, male patients had lower odds of viral suppression aOR: 0.69 (0.62-0.77). Compared with ART duration of 6-12 months, ART for 2-5, above 5-10 or more than 10 years was associated with poor viral suppression (P < 0.001). Dedicated adolescent space, rapid viral load turnaround time, and tailored approaches for male individuals and perinatally infected AYA may improve viral suppression. Routine summarization of viral load suppression in clinics could provide benchmarking to motivate innovations in clinic-AYA and individual-AYA care strategies.