This study investigated discrete achievement emotions (enjoyment, pride, boredom, and anxiety) as simultaneous mediators between achievement goals (mastery goals, performance-approach goals, and performance-avoidance goals) and academic engagement (cognitive engagement, effort withdrawal, and novelty avoidance). The data were collected using an online questionnaire with a sample of secondary school students (n = 1939) in Singapore. With gender, stream, and grade controlled, we conducted structural equation modelling to test the hypothesised mediation model. We found that achievement goals had a differential relationship with the four achievement emotions, which in turn showed a distinct association with engagement variables. Achievement emotions as mediators partly explained the differential relationship between achievement goals and academic engagement. In particular, the findings highlight the complex meaning of enjoyment and anxiety and the adaptive role of mastery goals in student learning.