<p>Multinational enterprises (MNEs) rely on information technologies (IT) to expand internationally and to manage their cross-border activities. Despite the implementation of stringent IT policies, they are increasingly confronted with Shadow IT, i.e., the use of non-authorized IT systems, devices, software, applications and services. This phenomenon is accentuated in cross-border acquisitions, but little is known about how MNEs can deal with Shadow IT when integrating new targets in foreign markets. To address this gap, we use the knowledge-based view (KBV) to investigate the role of Shadow IT in the integration process of cross-border acquisitions. We built a single case study of a German MNE in the biotechnology industry, which has expanded globally through cross-border acquisitions. The empirical study is based on 19 semi-structured interviews conducted with managers in the acquiring and target companies. Our findings highlight how IT can support the integration process in cross-border acquisitions. We offer novel insights into the ambivalent role played by Shadow IT, which can facilitate the integration process despite the risks inherent to unauthorized IT systems and tools. Our study contributes to rejuvenating research on cross-border acquisitions by uncovering a hidden pattern that has been overlooked in previous literature.</p>