Effective teaching and learning and academic performance is affected by several factors which includes parent social economic status, school facilities, motivation, students' attitude towards mathematics. The study was a descriptive study of survey type and supported qualitatively. Questionnaire and interview were employed for data collection. The target population for this study comprised of all the three thousand four hundred and sixty (3,460) senior secondary school II (SS 2) mathematics students and their teachers in Ilorin South, Kwara State (Kwara State Universal Basic Education, 2019). Multi-stage sampling technique was used for the sampling process. In the first stage, four (4) wards in Ilorin south Local Government Area were selected randomly through balloting method namely: Akanbi ward III; Akanbi ward IV; Akanbi ward V and Okaka ward I. In the second stage, balloting method was used to select two (2) schools each from the four (4) wards making a total of eight (8) schools. In the third stage, twenty percent (20%) of the students in each of these schools were selected through systematic random sampling technique. The questionnaires were filled by three hundred and forty-six (346) students and ten (10) mathematics teachers making a total of 356 respondents. Furthermore, out of the 356 respondents eight (8) students and ten (10) mathematics teachers were interviewed. Demographic data of respondents were analysed using frequency counts and percentages while the research questions were also descriptively answered using frequency and percentage. The study revealed that: (i) teacher's qualification have an influence on effective teaching and learning of mathematics in schools (ii) teacher's experience does not have influence on effective teaching and learning of Mathematics in schools (iii) availability and use of instructional material influence effective teaching and learning of Mathematics in secondary schools (iv) school facilities and equipment and other teaching material was also found to have influence on effective teaching and learning of mathematics in secondary schools (v) Teachers' teaching experiences is the most influential factor affecting effective teaching and learning of mathematics.