Background: Malnutrition is a health concern worldwide since the number of undernourished people is still high. In Kenya, the current food supply situation and outlook is a cause of concern. Majority of Kenyan children aged 6-59 months especially those living in the arid and semi-arid lands are undernourished because of household food insecurity. In Kitui County, one of the arid parts of the lower eastern Kenya, stunting levels were at forty six percent in 2014, almost double the national rate. To improve the nutritional status of the children, the dietary practices and water and sanitation situation need to be established. Objective: The objective of this study was to assess the dietary practices and nutritional status of children 6-59 months as well as water and sanitation situation in Kitui County. Methods: A cross sectional analytical study was conducted among 262 children from 167 households randomly selected in Mwingi Central Sub-County of the arid Kitui County. The respondents were primary caregivers of the study children. Data from structured questionnaire was analyzed using SPSS software, Version 21. To establish children’s nutritional status, WHO, 2006 growth standards were used to analyze children’s anthropometric data. Multiple linear regression was used to establish the relationship between variables. Significance level was set at p<0.05. Results: The mean Dietary Diversity Score (DDS) for the children aged 6-23 months was 2.8 which was less than the recommended Minimum Dietary Diversity of ≥4 food groups per day for both breast fed and non-breastfed children. Grains, roots or tubers; was the most consumed food group. Almost all the households used unsafe water and covered a distance of more than 500 metres to the water source. Majority of the households disposed the human waste and child excreta hygienically. The levels of wasting, stunting and underweight was 12.2%, 27.9% and15.8% respectively. The boys were more affected in both underweight and stunting. About 16% of both boys and girls were wasted. Conclusion: Arid and harsh climatic conditions limit dietary diversity and strain water availability compromising sanitation hence negatively affecting nutritional status.