Purpose: By providing equal weight to buyers and sellers, the purpose of this paper is to enhance our understanding of the determinants underlying successful mergers and acquisitions (M&As) involving a specific segment of firms involved in such undertakings, i.e., knowledge-intensive innovative and entrepreneurial (KIE) firms. Design/methodology/approach: A multiple case study, based on eight semi-structured interviews with CEOs representing acquirers and the acquired firms, investigates the focal phenomenon this study addresses. Findings: The results suggest that knowledge-intensive, innovative and entrepreneurial firms promote entrepreneurial intentions and allow value creation of M&As through four overarching measures. These are buyer–seller fit, aligned incentives, long-term thinking and perpetual alliance. Research limitations/implications: The outcomes of this research may have limited generalizable due to the chosen research methodology. Therefore, this study recommends future studies testing the validity of these findings. Practical implications: The authors have clarified the drawbacks of integration when being involved in M&As with KIE firms. These drawbacks primarily revolved around not eliminating the entrepreneurs’ autonomy and their routines, but it is also partly related to letting them keep their identity (i.e. their brand) as well as retaining employees’ trust in the new owner. Originality/value: Contrary to most papers, this study has taken an approach giving equal weight to both buyers and sellers. In doing so, this study clarified the drawbacks of integration when it involves M&As with KIE firms. © 2023, Viktor Ström, Pontus Braunerhjelm and Saeid Esmaeilzadeh.