Background <p>Early childhood development in low-resource settings remains poorly characterized, limiting targeted interventions. This study was aimed to assess child development and its determinants among infants at aged six months in Bench Sheko Zone, Southwest People’s Region.</p> Methods <p>A community-based cross-sectional baseline assessment was conducted among 375 children nested within 12 purposively selected kebeles (clusters). Developmental outcomes were measured using the Ages and Stages Questionnaire, Third Edition (ASQ-3) and the ASQ: Social-Emotional, Second Edition (ASQ: SE-2). Independent variables were selected a priori based on the WHO/UNICEF Nurturing Care Framework, encompassing domains of health, nutrition, responsive caregiving, safety and security, and early learning opportunities. Data were collected via face-to-face interviews with primary caregivers and direct observation of caregiver-child interaction. To account for within-kebele clustering, generalized estimating equations (GEE) with an exchangeable working correlation structure and robust standard errors were used. Intra-cluster correlation coefficients were estimated for each developmental domain. To address multiple hypothesis testing, the Benjamini-Hochberg procedure was applied to control the false discovery rate (FDR) at 0.10. All analyses were conducted in Stata version 15.0.</p> Results <p>Among 375 6-month-olds, mean ASQ-3 scores were: fine motor 38.12 (SD 12.46), communication 35.77 (SD 11.03), problem solving 35.52 (SD 12.01), personal-social 35.02 (SD 10.37), and gross motor 34.49 (SD 13.27). Mean ASQ-SE2 score (higher=more difficulties) was 86.18 (SD 43.54). ICCs ranged 0.02–0.09. After FDR correction, responsive caregiving (β = 3.24) and higher caregiver education (β = 5.49–4.62) predicted better problem solving. Normal weight (β = 2.90) and food security (β = 3.36) were associated with higher personal-social scores. Fewer children under five (β=–3.83 to − 11.24), food security (β = 3.06), partner involvement (β = 2.56), and absence of maternal depression predicted better communication. Paternal secondary education (β = 6.66) and non-farming occupation predicted higher fine motor scores. Urban residence was associated with lower ASQ-SE2 scores (β=–28.46, fewer difficulties), while higher paternal education unexpectedly predicted higher (worse) ASQ-SE2 scores.</p> Conclusions <p>Domain-specific developmental patterns and predictors aligned with the Nurturing Care Framework were identified, including responsive caregiving, nutrition, food security, sibling number, and paternal factors. These findings inform Zonal health offices to strengthen HEW-delivered integrated nutrition and stimulation during growth monitoring/vaccination contacts, with targeted support for high-risk infants. The upcoming cluster RCT should combine responsive caregiving coaching, nutrition support, stress-reduction modules, and enhanced rural delivery to generate actionable evidence for early child development programs and Ethiopia’s Health Extension Program.</p> Trial Registration <p>Registered at Pan African Clinical Trial Registry (PACTR202501678782291) 23 January 2025.</p>