Bipolar DC microgrids have attracted widespread attention due to their high flexibility, reliability, and compatibility. However, they also face challenges, such as voltage imbalance between poles. To address the problem of voltage deviation caused by unbalanced power distribution between source and load in bipolar DC microgrids, an isolated DC/DC converter with bipolar output voltage self-balancing capability is proposed. The proposed converter consists of a phase-shifting full-bridge inverter unit and an adjustable bipolar voltage gain unit, which can effectively support the automatic voltage balancing between the poles in a bipolar DC microgrid. It also features simple control and expandable structure. First, the derivation process of the proposed converter is elaborated in detail, and the working principles under different modes are presented. Then, an in-depth analysis is conducted on voltage gain, device stress, self-balancing principle, and loss calculation. Finally, a 1 kW experimental prototype is built to verify the theoretical analysis. Experimental results demonstrate that the proposed converter exhibits excellent bipolar output voltage self-balancing capability.