The article addresses the considerations concerning key issues affecting the proper functioning of enterprises. The global situation related to the COVID-19 pandemic in recent years has contributed to significant changes in terms of management. In this publication, the attention is drawn to a necessary element of the functioning of enterprises, i.e., knowledge management. Actions taken in the field of implementing innovation, implementing IT systems as well as implementing the concepts of sustainable development translate into proper knowledge management in enterprises. The above issues are defined and constantly deepened in literature. However, there are few studies that combine this topic and analyze interrelationships. The review of literature indicates the significance of these issues and confirms the need for further research in this area. In this publication, the issue of innovation is addressed, as a “driving wheel” of enterprises operating in the market environment. The link between the implementation of innovation in enterprises and the development of IT systems, taking into account the idea of sustainable development, is also analyzed. The considerations are deepened by the relations between knowledge management and innovation, IT systems and sustainable development. The article includes the empirical part in which two enterprises from Poland, operating primarily on the domestic market, are subject to the analysis. In the article, a case study has been applied using economic analysis based on two selected enterprises. The objective of the article has been to learn about the components of knowledge management used in crisis conditions. It should be noted that the pandemic period was a crisis situation for enterprises and the conducted research has showed what actions in terms of knowledge management were taken by enterprises to survive on the market. The conducted analyses have proved that enterprises, despite the same industry, took different actions, which translated to the achieved financial results. The functioning of modern enterprises in crisis conditions, taking into account the issues discussed in the article, is the key to their success. Therefore, the topic of the article is up-to-date and relevant.