In the present study, we aimed to develop and apply a model to evaluate the social, economic, and environmental sustainability of dairy production systems (DPS). In addition, we sought to analyze structural and production characteristics of DPS of different sustainability levels. Semi-structured questionnaires were used to collect structural and production data as well as information on sustainability actions taken by rural producers in 152 DPS located in Paraná, Brazil. The proposed model was applied to analyze the data. Each DPS received a score to represent its level of social, environmental, and economic sustainability, and DPS with similar sustainability levels were grouped according to these indicators using hierarchical cluster analysis. Three groups were formed: G1, comprising the largest proportion of DPS (63.8%); G2 comprising 20.4% of DPS; and G3, comprising 15.8% of DPS. The mean values of the sustainability indicators of each group were compared to those of other groups using analysis of variance (ANOVA) and Tukey’s test. Subsequently, groups were analyzed in terms of structural and production characteristics. G2 was characterized by the highest levels of environmental, social, and economic sustainability. G1 had intermediate sustainability levels, and G3 achieved the worst results in the three sustainability indicators. The best sustainability performance of the three DPS groups was in the environmental dimension, followed by the economic dimension and lastly the social dimension. DPS with large-scale production and high productivity showed the highest sustainability indicators. The sustainability assessment model was suitable for DPS, having the advantages of being easy to apply, easy to interpret, and low cost.