Purpose: The purpose of this article is to discuss isomorphic mechanisms which accompany the process of projectification in the Polish public sector. Design/methodology/approach: Research material used to develop this text was gathered during a comprehensive research project conducted between 2017 and 2020. The project utilized the instrumental case study method, focusing on the phenomenon of projectification within the Polish public sector. It employed a combination of quantitative and qualitative research techniques, such as document analysis, quantitative data analysis, and in-depth interviews. Findings: The study revealed that isomorphic mechanisms (coercive, mimetic, and normative), which lead to the projectification of the Polish public sector, appear at the macro level (sector), meso level (public organizations), and micro level (public sector employees) of the projectification research. Depending on the level of analysis of the phenomenon of projectification, different forms of isomorphic mechanisms dominate. At the macro level, which covers the entire sector and its public policies, coercive mechanisms played a central role. At the meso level, within organizations, both mimetic and coercive mechanisms proved crucial. Normative mechanisms, in turn, held prominence at the micro level, that is, among public sector employees. It is important to note that these mechanisms often intertwined and overlapped with each other. The article describes numerous examples of specific isomorphic mechanisms that manifest themselves in the studied organizational field. Research limitations/implications: The study examined a limited sample of public projects carried out in Poland and several public organizations. In the future, it would be worthwhile to consider a broader context, taking into consideration business and non-governmental organizations as well. This would facilitate a deeper reflection on those isomorphic mechanisms which support the projectification process within a broader scope. Practical implications: In practical terms, this study makes it possible to comprehend the mechanisms that drive the transfer of project knowledge and bring about organizational and structural transformations within the public sector. These mechanisms can aid practitioners in terms of deepening their reflection on seemingly unnoticed yet significant changes which take place in project-based organizations. Originality/value: The article presents a fresh perspective on the understanding of projectification processes based on isomorphic mechanisms.(original abstract)