The study utilized data from the adoption pathway survey and utility maximization theory to examine the impacts of adopting multiple sustainable agricultural practices (SAPs) on food security, nutrition, and poverty among smallholder maize farmers in the Morogoro region of Tanzania. The SAPs considered include manure, crop rotation, intercropping, crop residuals, and improved maize varieties. Using the endogenous treatment effect model, data collected from 470 farming households in Kilosa and Mvomero districts through a multi-stage sampling procedure were analyzed. Prior to data analysis, weak instrument and zero first-stage tests were employed to test the robustness and validity of the selected instruments, with results deemed satisfactory. The empirical findings indicate that the application of improved maize varieties, crop residual, and crop rotation had positive and significant impacts on the household’s food security and nutrition. Notably, the usage of improved maize varieties alone demonstrated positive and significant impacts on the poverty indicators, suggesting its potential to alleviate poverty among smallholder farmers. The study recommends the development of agricultural productivity enhancement programmes. These programmes should feature a precise targeting strategy aimed at food-insecure households and poor farming households, with the goal of eradicating hunger and nutrition deficiencies within these vulnerable groups. Furthermore, the poverty-alleviating impacts of SAPs, such as the application of improved maize varieties, are expected to grow with increased adoption. Consequently, it is crucial to prioritize significant investments in agriculture. Strengthening and improving maize seed systems becomes imperative, aiming to guarantee the availability and affordability of enhanced maize varieties for smallholder farmers in Tanzania. This step will facilitate wider adoption and contribute to poverty reduction among farming communities.