Sustainable livestock farming practices have the potential to improve productivity and high income, reduce greenhouse gases, and improve household food security. Despite previous efforts to disseminate these technologies, the rate of adoption has remained very low in Ethiopia. In this study, we investigate the determinants of adoption and the impact of improved dairy farming practices (IDFP), which include improved breed, improved feed, and improved feeding conditions, on household food security in the central highland of Ethiopia. A multi-stage stratified random sampling technique was used to select 480 smallholder farmers from four districts. The study employed principal component analysis (PCA) to group IDFPs, and the endogenous switching regression model (MESR) was used to examine household food security status. Our findings showed that IDFP adoption had a significant and positive impact on per capita food consumption and increases the likelihood of smallholder farmers being food secure compared to non-adopters. The adoption of integrated IDFP had a greater impact on household food security when smallholder farmers used a package that incorporates improved breeds, feeds, and feeding systems (B1F1S1). The implementation of this package increased food security by 31% in terms of household food consumption score (HFCS) and 26% in terms of household diet diversity score (HDDS). Additionally, the size of livestock holdings, off-farm income, extension services, and milk collection centers all influenced the adoption decision of this package. It has been confirmed that improving dairy farming practices for sustainable development can significantly contribute to the food security of smallholder farmers when used in combination. Interventions that address access to farm resources, the supply chain for technological inputs and services, and output markets may assist in the adoption of dairy technologies.