The study evaluated the relevance and effectiveness of primary school teachers' professional development policy and practices in Oromia Regional State. The researcher used a mixed method with concurrent triangulation design. The researcher selected a total of 618 samples of the study using different sampling techniques such as purposive, convenience, stratified, and simple random sampling techniques. The data were collected from primary sources of data such as teachers, mentors, principals, supervisors, coordinating committees, and parents using questionnaires, interview, focus group discussion, document examination, and observation. The researcher analyzed the data using mean, standard deviation, one-way ANOVA and post-hoc test, and thematic narration. The findings of study showed that teachers' professional development practices were powerless to update professional competencies and improve professional and innovative pedagogical practices in classrooms. Primary school teachers were not learning proficiently from continuous professional development practices to ensure basic and specific professional competencies required in classrooms. The implementations of reflective activities such as action researches, classroom observation, differentiated learning, collaborative learning, microteaching, and lesson studies couldn't contribute to practical changes. The study forecasts the requirement of context specific policy framework and practical toolkit for newly deployed and experienced teachers rather than focusing on the generic policy document.