To improve outcomes among HIV-positive adolescents, the Malawi Ministry of Health is supporting scale-up of "Teen Clubs," a facility-based antiretroviral treatment (ART) delivery model. Teen Clubs are monthly ART clinics for adolescents (10-19 years old) that provide clinical services and peer psychosocial support. This paper assesses ART adherence among Teen Club attendees in Malawi. We performed a retrospective analysis of medical records and Teen Club attendance data on 589 HIV-positive adolescents at 16 Partners in Hope (PIH)-Extending Quality Improvement for HIV/AIDS in Malawi (EQUIP) supported facilities across Malawi, from January to June of 2017, who attended at least two Teen Club sessions. Multi-level logistic regression models were used to examine the role of gender and age on optimal ART adherence (≥ 95% based on pill count) among HIV-positive adolescents enrolled in Teen Clubs. The median age of adolescents in this sample was 14 years, and 47% were male. Older adolescent males (15-19 years) were 64% more likely to achieve ≥ 95% ART adherence (aOR 1.64, 95% CI 1.16-2.31, p < 0.01) compared to younger (10-14 years) males. The effect of age on adherence was smaller and not significant among females (aOR 1.36, 95% CI 0.96-1.94, p = 0.08). In the full model including males and females, older adolescence was associated with higher odds of optimal adherence (aOR 1.48, 95% CI 1.16-1.90, p < 0.01). These results reinforce the need for age-specialized programming for adolescents, and future research should evaluate this in achieving optimal ART adherence.