Control-value theory proposes that achievement emotions impact achievement, and that achievement outcomes (i.e., success and failure) reciprocally influence the development of achievement emotions. Academic buoyancy is an adaptive response to minor academic adversity, and might, therefore, offer protection from achievement being undermined by negative achievement emotions. At present, however, there is little empirical evidence for these hypothesized relations. In this study we examined reciprocal relations between three achievement emotions (enjoyment, boredom, and anxiety) and test performance in the context of mathematics, and whether academic buoyancy moderated relations between these emotions and test performance. Data were collected from 1,242 primary school students (mean age = 9.3 years) over four waves within one school year. Achievement emotions (T1 and T3) and test performance (T2 and T4) were measured alternately. Academic buoyancy was measured at T3. A structural equation model showed negative relations of anxiety to subsequent test performance, and negative relations of test performance to subsequent anxiety. Test performance also predicted enjoyment and boredom, but not vice versa. A latent-interaction structural equation model showed buoyancy moderated relations between anxiety and test performance. Test performance was highest when anxiety was low and buoyancy high. Practitioners should consider using interventions to reduce anxiety and downstream effects on achievement.