Public procurement is now a means to achieve strategic goals and not just an administrative procedure for the procurement of goods, services or works and is also an important tool for achieving changes through social relations, environmental aspects and the economic system, therefore the topic of sustainability becomes absolutely unavoidable. The subject of this postgraduate specialist thesis is research on the implementation of sustainable public procurement criteria through a comparison of public and sectoral contracting authorities. Through a detailed analysis, we have determined the current knowledge on the topic of sustainable public procurement, the development of sustainable public procurement, legislation development and sustainability criteria through judicial practice in the European Union, and in order to investigate the implementation of the criteria of sustainable public procurement, a case study analysis methodology is carried out through which we have compared implementation of sustainability criteria with public and sectoral contracting authorities. In parallel with sustainability, digitalization is also taking place, which supports it and is intertwined with each other. The main conclusions of the research are that the implementation of prescribed sustainability criteria into public procurement procedures introduces uniformity of criteria, compliance, generation of new jobs, but it can also result in a drop in competition and higher costs.