Background: Systematically registering ADRs in electronic health records (EHRs) likely contribute to patient safety as it enables the exchange of drug safety data. Currently, ADRs registrations by healthcare professionals (HCPs) is suboptimal. This study aimed to identify barriers and facilitators perceived by HCPs to register ADRs systematically in EHRs. Research Design and Methods: A qualitative study with individual interviews was conducted among specialist physicians and hospital pharmacists from 10 different Dutch hospitals. A semi-structured interview guide was used to identify experienced barriers and facilitators for systematically registering ADRs. Data was analyzed following thematic analysis. Themes within barriers and facilitators were aligned with the Capability–Opportunity-Motivation–Behavior (COM-B) framework. Results: In total, 16 HCPs were interviewed. Identified barriers were: lack of knowledge to recognize ADRs, time constraints, inadequate IT system, lack of support, stuck in routine, and not recognizing the importance of registering ADRs. Identified facilitators were: enhanced knowledge and awareness of ADRs, functional IT systems, expanding accountability for registration, and motivation toward registering. Conclusions: Barriers and facilitators for registering spanned all aspects of the COM-B model and occurred in individual, social and environmental domains. Addressing these aspects could improve the registration of ADRs and may contribute to patient safety.