Open Educational Resources (OERs) are increasingly recognised as mechanisms for enhancing curriculum quality and expanding equitable access to educational resources; however, empirical evidence on their adoption in sub-Saharan African secondary education remains limited. This study investigated technology transfer practices and OER utilisation among secondary school teachers, guided by the Technology Acceptance Model and Diffusion of Innovations theory. Adopting a post-positivist research paradigm, the study employed an explanatory sequential mixed-methods design. Data were collected from 70 participants (56 teachers and 14 administrators) across 10 stratified-randomly selected secondary schools in Kigamboni District, Tanzania. Findings reveal that 87.5% of teachers were aware of OERs and 71.4% frequently integrated them into curriculum delivery through AI tools, educational videos, and curriculum-aligned lesson plans, mainly accessed via mobile devices. Chi-square analysis demonstrated a statistically significant association between technology transfer practices and OER utilisation levels (χ²(1)=8.42, p<0.01). Nevertheless, poor internet connectivity, fragmented training, and absent curriculum policies constrained sustained integration. The findings indicate that the perceived usefulness of OERs was high, while perceived ease of use was limited by infrastructure deficits. The study highlights the need for OER-aligned policies, digital infrastructure investment, and structured professional development to support effective and sustainable OER adoption in Tanzania across similar contexts. This study advances understanding of technology transfer and Open Educational Resource (OER) utilisation in Tanzanian secondary schools by providing context-specific empirical evidence on adoption practices, implementation challenges, and emerging opportunities. The findings reveal that although teachers acknowledge the pedagogical value of OERs and their potential to enhance access to quality learning materials, effective utilisation remains limited by systemic barriers, including inadequate digital infrastructure, restricted access to devices, insufficient professional development, and limited institutional support. By identifying these constraints, the study provides evidence-based insights to inform policymakers, education planners, school administrators, and development stakeholders in designing targeted strategies for sustainable digital transformation in secondary education. The study also contributes to scholarship by extending the application of technology adoption and educational integration frameworks, particularly the Technology Acceptance Model (TAM), Technological Pedagogical Content Knowledge (TPACK), and Diffusion of Innovations Theory, within a developing country context. The evidence generated supports the need for integrated approaches that combine infrastructure investment, teacher capacity development, curriculum-responsive OER platforms, and supportive policy frameworks. Ultimately, the study contributes to ongoing efforts to promote equitable digital learning environments, strengthen teaching and learning practices, and improve educational outcomes in Tanzania and comparable resource-constrained contexts.