This volume constitutes the refereed proceedings of the 7th International Conference on Modelling and Development of Intelligent Systems, MDIS 2020, held in Sibiu, Romania, in October 2020. Due to the COVID-19 pandemic the conference was held online. The 25 revised full papers presented in the volume were carefully reviewed and selected from 57 submissions. The papers are organized in topical sections on evolutionary computing; intelligent systems for decision support; machine learning; mathematical models for development of intelligent systems; modelling and optimization of dynamic systems; ontology engineering.