Student engagement is a multidimensional construct that predicts learning performance. However, student engagement receives limited attention, especially in mathematics. Thus, this study conducts a survey to determine the influence of student engagement on mathematical achievement. Stratified random sampling was employed to select secondary school students (n = 1000). Questionnaires and end-of-year examination grades were collected as data on student engagement and respective mathematics achievement. The findings indicate that there is a significant relationship between cognitive engagement, affective engagement, behavioural engagement, and mathematical achievement. The results of multiple linear regression analysis show that affective engagement is the largest predictor of mathematical achievement (β = 0.743, p < 0.001), followed by behavioural engagement (β = 0.585, p < 0.001), and cognitive engagement (β = −0.375, p < 0.01). This suggests that policymakers should formulate a curriculum that enables the improvement of affective and behavioural engagement. Furthermore, this study recommends that school administrators and teachers plan and implement activities that stimulate such engagement.