The use of Resource Description and Access (RDA) has become a strategic imperative for academic libraries seeking to remain relevant within the global information ecosystem, yet institutional readiness for its use in Nigerian federal university libraries remains largely under-explored. This study investigated the challenges of institutional readiness to use RDA for knowledge organization in Nigerian federal university libraries, drawing on the perspectives of university librarians and heads of cataloguing units who shape policy and implementation decisions. Adopting a qualitative research design, the study purposively selected nine federal university libraries out of fifty in Nigeria, based on the presence of an Integrated Library System and a functional Online Public Access Catalogue. Eighteen library management personnel were interviewed using a semi-structured guide, and data were analyzed thematically following Braun and Clarke's six-phase framework. Findings revealed eight interrelated challenges undermining institutional readiness: poor library automation, inadequate funding, absence of the RDA Toolkit, inadequate training, lack of specialized skills, poor use of RDA-compatible metadata & library systems, absence of guidelines and standards for RDA use, and limited understanding the concept of RDA. Also revealed was that, the challenges affect librarians' experiences, as they are still inclined to AACR2 that they are more familiar with. Librarians agreed that they need to unlearn old ways and learn new ways of cataloguing. The study recommends the development of comprehensive cataloguing policies, subscription to the RDA Toolkit, adoption of RDA-compatible systems beyond MARC21, sustained training partnerships, dedicated budgetary advocacy, and coordinated collaboration among stakeholders such as the NLA, NUC, AULNU, and LRCN to strengthen sustainable RDA use across Nigerian federal university libraries