Sustainable agricultural intensification (SAI) practices have been promoted in developing countries to improve farm productivity and environmental services. However, it is still unclear whether use of a combination of SAI practices has a significant influence on the cost efficiency of smallholder farms. This study investigates whether the cost efficiency of smallholder maize producers in Ethiopia depends on use of input-augmenting and agronomic SAI practices. Stochastic cost frontier models that account for heterogeneity across farms are used for estimation. We find that the use of individual SAI practices increases cost while the combined use of the practices reduces it. The marginal effect on cost reduction is substantial when SAI practices are set at their sample maximum levels. Overall, the results demonstrate the benefit of using a combination of SAI practices in minimizing production cost while addressing the adverse effects of soil degradation and climate variability. To enhance food security, smallholder farm incomes and the sustainability of production in developing countries, policy programs should focus on promoting packages of input-augmenting and agronomic SAI practices.