In spite of the place of mathematics in the Nigerian education system, the performance of students in both external and internal examinations is on the downward trend. Research on factors affecting students' achievement in mathematics has often neglected the impact of psychological variables, such as emotional intelligence, self-esteem, and self-efficacy. This study, therefore, was designed to study how emotional intelligence, self-esteem and the self-efficacy of students predict their academic achievement in mathematics. The correlational survey research design was employed with a population of 2,937 senior secondary 2 students and a sample of 400 students sampled from 16 secondary schools in the Nnewi Education zone of Anambra State. Emotional intelligence, Self-esteem, Self-efficacy Questionnaires, and Students' Academic Achievement Score Form (SAASF) were used to collect data through the direct delivery method. Data were analyzed using simple linear regression analysis. The results showed that emotional intelligence, self-esteem, and self-efficacy had significant predictive powers on students' academic achievement in mathematics. Thus, emotional intelligence, self-esteem, and the self-efficacy of students are prime determinants of their achievement in mathematics. It was recommended that students should be taught using methods that will enhance their emotional intelligence, self-esteem, and self-efficacy.