Teachers’ understanding of the concept competence-based curriculum, competences demonstrated in preparing of competence-based curriculum materials, competences in integrating competence-based curriculum materials with actual classroom teaching, and teachers’ competences to address challenges in the implementation of competence-based curriculum were the objectives of the study. The study investigated on teachers’ instructional competences in the implementation of competence-based curriculum. Mpwapwa District Council was a case of this study. The study sample size was drawn using purposeful techniques. A total of 24 participants from 6 primary schools were involved in this study. 18 out of 24 participants were classroom teachers, and 6 were Head-teachers. The study used qualitative approach to capture participants’ views. Document review, observation, and interview methods were employed for data collection. Data were analyzed through thematic and content techniques. The findings revealed that teachers understand competence-based curriculum as activity and application oriented curriculum. Further, the findings showed that teachers use inappropriate verbs in preparing scheme of works and lesson plans. Moreover, the study found that teachers possess adequate instructional competences however, large classes and shortage of text books hindered them to effectively integrate the curriculum materials; lesson plans with actual classroom implementation of the curriculum. Additionally, it was found that teachers have reasonable competences to overcome challenges in the implementation of competence-based curriculum. The study concluded that despite the noted disparities, teachers possess and use instructional competences effectively to implement the curriculum. However, for higher adeptness in the implementation of competence-based curriculum it is recommended that formal trainings should be given to all teachers in the District. Also schools should be provided with adequate text books. Importantly, the present teachers should be redeployed equally to all schools.