Students can perform well in mathematics only if student diversity is appropriately addressed. However, limited studies in Philippine schools have explored the use of differentiated instruction (DI) to address student diversity and improve numeracy skills. In the local context, students at San Pedro Relocation Center National High School demonstrated poor numeracy skills, as reflected in previous test results. To address this, DI strategies were implemented in mathematics classrooms to enhance numeracy by catering to diverse student needs. This study aimed to improve students' numeracy skills through DI strategies such as assessing prior knowledge, using open-ended questions, assigning parallel tasks, and integrating technology. A practical action research design using the plan-do-study-act model was employed over a three-month period in one school. Participants included twenty mathematics teachers who underwent training through Learning Action Cell (LAC) sessions and 5,300 students from Grades 7 to 11. Data were collected using teacher-made tests, an adapted questionnaire, and interviews, all validated by mathematics education experts. The results showed that DI strategies effectively addressed student diversity by delivering lessons based on students’ interests, readiness levels, and learning preferences. Providing students with options for demonstrating competencies increased their engagement in learning. Students’ numeracy skills significantly improved, as evidenced by test scores following the integration of DI strategies. However, teachers faced challenges such as limited pedagogical skills, lack of resources, time-consuming implementation, and classroom management difficulties. Despite these issues, DI strategies proved effective in addressing student diversity and improving numeracy skills among students.