The adoption of Information and Communication Technology in Tanzanian higher education institutions has led to the implementation of different but equivalent Academic Information Systems to support the management of different activities of students. However, these systems are not well used to support decision-making in those institutions. This study applied the Unified Theory of Acceptance and Use of Technology model to study the perceptions of decision makers on the use of academic information systems in their daily activities, especially in decision-making. A mixed methods approach was followed, whereby questionnaires and interviews were used for data collection. Regression analysis was done to test the research hypotheses, and the qualitative data were thematically analyzed. The results showed that performance expectancy and facilitating conditions predicted the behavioral intention to use the systems (p<0.05) while effort expectancy and social influence were statistically insignificant (p>0.05). It was also found that users like to use the system, but undesirable functionalities, lack of necessary data, poor support, and inadequate training undermine their will to use the systems for decision-making. The results obtained cast new light on various issues that hinder the use of academic information systems by decision makers, and point toward new measures to improve them in order to increase their adoption.