The internet of things (IoT) has revolutionized various sectors, including agriculture. Accurate predictions of agricultural yields can help farmers and agriculturalists optimize land and resource management. One of the important plants in the agricultural industry is citrus plants. This study aims to develop an IoT-based prototype that utilizes Mamdani type fuzzy logic to predict citrus agricultural yields. Fuzzy logic is used because it is able to handle the uncertainty and complexity of agricultural environmental data. The Mamdani fuzzy logic model was built by considering input variables from sensors and linguistic rules provided by agricultural experts. The output of this fuzzy logic system is predictions regarding orange yields, which can assist farmers in making decisions regarding plant care. The results show that the proposed prototype is able to provide predictions of orange yields with a sufficient degree of accuracy. The integration between IoT and Mamdani fuzzy logic provides an efficient and effective way of optimizing the management of citrus farms.