The rapid inclusion of online assessment in higher education has left a void in investigating the relationship this form of assessment has with student emotions. This study examines the influence of frequent online assessment on student emotions in a university setting using a mixed-methods approach. Students' emotions in an online quiz and a traditional classroom test in a second-year mathematics course (n = 91) were analysed using both quantitative and qualitative approaches, through the lens of the control-value theory. The study used an adaptation of the Achievement Emotions Questionnaire (AEQ) to collect data on reported student emotions in both assessments, as well as qualitative data on student's views of the frequent online assessment. Students reported higher levels of positive emotions and lower levels of negative emotions in an online quiz compared to the test, and we attempted to identify sources of these differences. The findings are discussed together with implications for habitualisation of assessment emotions. Practically grounded generalisations are outlined as opportunities for disrupting negative emotions and reaffirming positive emotions, which are suitable for implementation in higher education on a broad scale.