Optimal complementary feeding practices play a vital role in the nutritional status of young children. In Kenya, significantly higher rates of acute malnutrition have been reported among pastoralist communities, particularly among children aged 6-23months. There is inadequate complementary feeding data on pastoralist communities despite their vulnerability. The objective of the study was to establish the determinants of complementary feeding practices and nutritional status of children 6-23 months among pastoralist communities of Isiolo County, Kenya. A cross-sectional analytical study using two-stage cluster sampling methodology was applied to select a sample of 288 children aged 6-23 months from pastoralist communities. Data on the socio-demographic characteristics of the study population, complementary feeding practices and anthropometric measurements of the children aged 6-23 months was collected and analysed. Overall, the prevalence of stunting, underweight and wasting was 19.1%, 7.3% and 5.2% respectively. A variation in malnutrition prevalence was observed with age of children, with the 18-23month age group showing a higher prevalence of all forms of undernutrition. Male children had significantly higher proportions of underweight and stunting (p ≤ 0.05). Complementary feeding practices were sub-optimal - minimum meal frequency (60.4%), minimum dietary diversity (35.4%) and minimum acceptable diet (25.3%). Child age, child sex, caregiver’s age, and caregiver education level were significant determinants for complementary feeding practices and nutritional status of children 6-23months (p ≤ 0.05). We recommend that community based approaches targeting pastoralist communities should address the basic cause of child malnutrition through nutrition education and women empowerment initiatives.