This study aimed at finding out the application of self-directed learning among adult learning in Tanzanian adult education. It took Ilemela and Nyamagana districts in Mwanza region as a case study. The researcher used research instruments like questionnaires and semi-structured interview to collect data. The study was guided to three objectives. First, to examine whether adult learners have an understanding of self-directed learning model, second, to asses if self-directed learning model is applied in Tanzanian adult education, third, to explore the challenges facing self- directed learning in adult education. The research findings reveal that the application of self-directed learning in adult education of Tanzanian adult education is applied to some centers full because of the availability of teaching and learning resources. Although self-directed learning is applied to some centers, there are some adult education centers which do not apply self-directed learning. These centers do not apply because of the inadequate of teaching and learning resources which supports self-directed leaning model. The research findings reveal that self-directed learning application to adult learners is faced with a dozen of challenges. For instance, inadequate teaching and learning resources, inadequate and insufficient budget for running adult education programme, inadequate permanent human adult education resources and infrastructures, low level of consciousness and awareness among community members on adult education and un supportive environment. The researcher has recommended that, the government should provide and lead deliberate efforts of improving adult education by providing adequate funds and plans for buying teaching and learning materials, paying salaries to human resources and constructing permanent infrastructures. Also civic education and encouragement on adult education should be provided. Lastly, learners, educators, government and community should recognize adult education. They should observe, mobilize and invest in adult education for building the community and nation.