K-12 public education in Brazil suffers from little investment in teacher training resulting in lack of support to foster pedagogical change through use of digital technological resources for pedagogical use. The use of Open Educational Resources (OER) in the K-12 public education sector enables teachers to have access to a wide variety of free sources and new ideas for planning and enhancing their lessons and affords teachers the possibility to improve their knowledge and skills in information and communication technologies (ICTs). There has been little empirical research on teachers’ use of OER in K-12. This case study addresses that gap, exploring what could be a set of guidelines for a teacher professional development program (TPD) on OER in Brazilian K-12 public schools by means of the development and delivery of a face-to-face OER professional development program (ODC). The study was conducted at one Brazilian fundamental education public school; quantitative data assessed the intention of the participants of the study to adopt and use OER; qualitative data identified barriers, learning needs and assessed learning outcomes upon completion of the ODC. The findings of this study suggest that ongoing facilitator support, practical, hands-on TPD can enhance teachers’ engagement and confidence with OER. This type of TPD holds the potential to provide teachers with the necessary support for scaffolding engagement and learning in order to progressively lead them to empowerment and provide them with the autonomy and confidence required to learn about OER. Findings also indicate that school administrations’ awareness and engagement with OER is imperative to provide the necessary support. The study proposes a set of guidelines for TPD in OER for stakeholders who wish to promote the adoption and use of OER in the Brazilian public fundamental education system as well as in other K-12 education systems of developing countries.