This study examines the role of mentorship and peer support networks in enhancing continuous professional development for teachers in Nigeria, particularly in resource-limited environments. Grounded in Wenger’s communities of practice (CoP) theory, the study highlights how these informal learning structures contribute to teacher effectiveness, instructional quality, and professional growth. A survey research design was adopted to explore teachers’ experiences with mentorship and peer support networks. The population of the study was made up of 2,400,000 teachers registered with the Teachers Registration Council of Nigeria (TRCN). A sample size of 400 was drawn from the population using the Taro Yamane formula. A 21-item questionnaire titled “Mentorship and Peer Support Networks in Teacher Development in Nigeria Questionnaire (MPSN-TDNQ)” was used for online data collection. Mean and standard deviation was used for data analysis. Findings reveal that regular feedback, collaborative learning, structured professional relationships, and shared problem-solving significantly contribute to teacher development. However, barriers such as inadequate funding, lack of institutional support, heavy workloads, and limited access to digital resources hinder effective implementation. To address these challenges, the study recommends integrating mentorship into teacher training programs, leveraging technology for virtual mentorship, fostering a culture of collaboration through policy interventions, and developing localized professional learning communities. Strengthening mentorship and peer support networks will enhance teacher effectiveness, improve educational outcomes, and ensure sustained professional growth, particularly in under-resourced settings. Future research should explore scalable mentorship models and their long-term impact on teacher retention and student achievement.