A smart grid features can be referred to as a two-way communication with all active network elements and decentralized resources such as under-load tap-changer (ULTC), capacitor, and distributed generation (DG) units. In the smart grid systems, the mentioned units are required to be well coordinated to keep the voltage within the standard range. Therefore, in this paper, a multi-agent controller based on type-2 fuzzy logic system (T2FLS) is utilized to coordinate the DG, ULTC, and load to regulate the voltage of the smart grid in the presence of noise and uncertainty. The proposed fuzzy system identifies the different parts of the smart grid as an agent (i.e. ULTC, DG, and load) and regulates the voltage by managing them. A 16-bus power system has been utilized to demonstrate the effectiveness of the proposed method. It has been shown that the proposed T2FLS controller outperforms the type-1 fuzzy controller and regulates the voltage in an appropriate way even in the presence of the different levels of measurement noise and uncertainty.