Learners play very significant roles in the teaching–learning process. Irrespective of how teachers teach, learners often have their own ways of learning. Three hundred senior secondary school II students selected from 10 senior secondary schools in Ilorin, Nigeria participated in the study. Simple random sampling technique was used to select 30 students from each of the 10 purposively sampled senior secondary schools. Data were collected using three instruments, namely, Chemistry Self-Efficacy Questionnaire, Chemistry Metacognition Questionnaire and Chemistry Achievement Test with reliability indices of 0.83, 0.73 and 0.86, respectively. Answers were provided to four research questions each of which has a corresponding hypothesis. The hypotheses were tested at 0.05 level of significance using Pearson Product Moment Correlation, regression and analysis of variance. Findings from the study indicates significant positive relationship among senior secondary school students’ Chemistry self-efficacy, metacognition and their achievement in Chemistry F(2, 297) = 332.482, p < 0.05. Keywords: Academic achievement, metacognition, self-efficacy, senior secondary schools.