Educational development remains a critical national priority in Nigeria, and the Universal Basic Education (UBE) Policy was introduced as a strategic intervention to guarantee free, compulsory, and quality basic education for every Nigerian child. Despite this, the extent to which institutional, administrative, socio-economic, and policy-related factors shape the implementation of the Policy, and the extent to which implementation has translated into measurable educational development, remain in need of systematic, state-specific assessment. The objectives of this study were to examine the factors influencing the implementation of the Universal Basic Education Policy in Nasarawa State, and to assess the extent to which its implementation has influenced educational development in the State. The study was anchored on the Policy Implementation Theory of Mazmanian and Sabatier (1983), complemented by Systems Theory (Von Bertalanffy, 1968; Katz & Kahn, 1978). A mixed research design was adopted, involving the collection and analysis of both quantitative and qualitative data. Quantitative data were obtained through the administration of questionnaires, while qualitative data were sourced from Key Informant Interviews and secondary materials such as scholarly literature and official reports. The study population comprised ten thousand, two hundred and forty-five (10,245) personnel of the Nasarawa State Universal Basic Education Board (NSUBEB), drawn from officials, education secretaries, head teachers, and classroom teachers across six selected Local Government Areas, namely Akwanga, Wamba, Karu, Keffi, Lafia, and Doma. The sample size was determined using Yamane's (1967) formula, yielding a sample size of 385, approximated to 389 for administration purposes. Out of the 389 questionnaires distributed, 381 were returned, while 8 were not returned. A multistage sampling technique combining simple random and purposive sampling was employed. The findings revealed that institutional, administrative, socio-economic, and policy-related factors all significantly influence the implementation of the Universal Basic Education Policy in Nasarawa State, with institutional factors rated marginally highest, and that the implementation of the Policy has significantly influenced educational development, most notably through increased school enrolment, with comparatively modest gains in educational infrastructure and learning outcomes. Based on these findings, the study recommends strengthened institutional coordination, targeted socio-economic support for vulnerable households, and increased investment in educational infrastructure to close the gap between access and quality in the implementation of the Universal Basic Education Policy in Nasarawa State.