Research on geographic differences in health focuses largely on children less than five years; little is known about adolescents-and even less regarding younger adolescents-a vulnerable group at a critical stage of the life course. Africa's rapid population growth and urbanization rates, coupled with stagnant rates of undernutrition, further indicate the need for country-specific data on rural-urban health disparities to inform development policies. This study examined rural-urban disparities in body mass index-for-age-and-sex (BAZ) and height-for-age-and-sex z-scores (HAZ) among younger adolescents in Tanzania. Participants were randomly selected adolescents aged 10-14 years (N = 1,125) residing in Kilosa (rural) and Moshi (urban) districts of Tanzania. Individual and household-level data were collected using surveys and anthropometric data was collected on all adolescents. Age, sex, household living conditions, and assets were self-reported. BAZ and HAZ were calculated using the WHO reference guide. The prevalence of undernutrition was 10.9% among rural and 5.1% among urban adolescents (p<0.001). Similarly, stunting prevalence was greater in rural (64.5%) than urban (3.1%) adolescents (p<0.001). After adjusting for covariates, rural residence was significantly and inversely associated with BAZ (B = -0.29, 95% CI: -0.52, -0.70, p = 0.01), as well as with HAZ (B = -1.79, 95% CI: -2.03, -1.54, p<0.001). Self-identified males had lower BAZ (B = -0.23, 95% CI: -0.34, -0.11, p<0.001) and HAZ (B = -0.22, 95% CI: -0.35, -0.09, p = 0.001) than self-identified female adolescents. Rural-urban disparities in nutritional status were significant and gendered. Findings confirm place of residence as a key determinant of BAZ and HAZ among younger adolescents in Tanzania. Targeted gender-sensitive interventions are needed to limit growth faltering and improve health outcomes in rural settings.