Background: Undernutrition is a universal public health problem for both children and adults globally. It is not only a public health concern but also an impediment to global poverty reduction, productivity, and economic growth. Under-five children are among the most vulnerable groups, although it affects both women, the elderly, and youth. This study assessed the influence of feeding practices on under-five nutrition status in Mbinga District, Tanzania. This paper unveils the contribution of feeding practices to underfive nutrition status in Tanzania. Methods: A cross-sectional study involved 150 heads of households whose children aged 0–59 months were assessed to determine their anthropometric measurements. Weigh for age Z-scores, height for age Z-scores, and weight for height Z-scores. A structured questionnaire was administered to collect data from the heads of households. Data were coded and analyzed by ENA for the SMART, Statistical Package for Social Sciences (SPSS), and STATA programs. Results: It is revealed that 90.7% of under-five children in the surveyed households initiated breastfeeding within one hour of life, 72% of the children were given complementary foods before six months, maize porridge was a major complementary food, and 80% of the children consumed three to four meals per day. Their diets were not diverse as starchy staple foods were dominant. It was further found that 42% of the children were stunted, 33% were wasted, and 25% were underweight. Moreover, the results of the ordered probit regression model showed that exclusive breastfeeding, meal frequency, and food dietary diversity were positively influencing nutrition status, while household size was negatively influencing the nutrition status of the under-five. Conclusion: The study concludes that inappropriate complementary feeding, children did not receive the minimum dietary diversity, and poor child feeding practices have a positive influence on the anthropometric status of the under-five. It was recommended that education be provided to community members on appropriate child feeding practices and family planning.