The study investigated the extent of mathematics curriculum implementation in Delta North Senatorial District. The study used a cross-sectional survey research design. The population of the study was 1,694 made up of 338 mathematics teachers and 1,356 mathematics students. The sample size of the study was 366 comprising of 183 mathematics teachers and 183 mathematics students using the stratified random sampling technique. Validated questionnaire was used for data collection. Data collected were analyzed using Mean and Standard Deviation. Findings showed that teachers’ mathematics proficiency, mathematics instructional materials and mathematics teaching method influences teaching of the subject. The study concluded that teacher proficiency is vital for effective curriculum implementation, instructional resources are essential for enhancing the teaching and learning process, and teaching methods significantly influence students' understanding of mathematics. The study therefore recommended among others that school authorities should lay more emphasis on the use of instructional materials in the teaching of mathematics in senior secondary school as the use of instructional materials will make the abstract teaching to look concrete.