This paper aims to design decentralized controllers for different components in islanded DC microgrids. The major components in the DC microgrid as considered in this paper include a fuel cell, solar photovoltaic (PV) unit, and battery energy storage system (BESS) along with critical and non-critical loads. The main control objective is to maintain the power balance within the DC microgrid through the regulation of the common DC-bus voltage. The controllers are designed based on the dynamical models of the fuel cell, solar PV unit, and BESS. The feedback linearization technique is employed to obtain the control laws, which simplifies the original dynamical models and decouples different components in the form of several subsystems. In this way, the feedback linearization technique allows different components in DC microgrids to achieve the desired control objectives by using only the local information (i.e., in a decentralized manner). The performance of the proposed decentralized controllers for different components is evaluated on a test DC microgrid under different operating conditions. Simulation results demonstrate that the proposed control scheme performs in a much better way as compared to an existing proportional integral controller.