Background: This study aims to identify how and if strategic procurement 4.0 performance influences competitiveness under circular economy conditions. In this regard, to achieve the aim of the study, we examine the moderating and mediating effects of strategic procurement 4.0 performance. In addition, the paper explores the role of procurement 4.0 in the circular economy and its impact on organizational competitiveness, with a focus on the mediating factors in the relationship between manager attitudes and competitiveness, making a significant contribution to the emerging research in this field. Methods: The results of a two-way moderated multiple regression analysis showed that there is an effect that intensifies the relationship between the variables being studied. Mediating effects were tested using Smart PLS-4 and the results showed significant mediating effects of strategy for procurement 4.0 and planning for procurement 4.0. Results: The study found that organizations with high strategic procurement 4.0 performance and high circular economy openness have the highest level of competitiveness. However, low levels of circular economy openness result in similar competitiveness levels regardless of low or average strategic procurement 4.0 performance. Conclusions: We found that strategic procurement 4.0, aligned with sustainability goals and incorporating digital technologies, leads to increased competitiveness in the context of the circular economy, as demonstrated in the Romanian business environment. Moreover, our study highlights the importance of strategic training in procurement 4.0, the need for a three-level approach in procurement strategy, planning, and performance review, and the significance of considering non-financial aspects in competitiveness and innovation within the context of a circular economy.