The power electronic loads usually behave as constant power loads (CPLs) in dc microgrids (MGs), which degrades the system stability due to their high-order nonlinearity and negative impedance characteristics. Furthermore, the stability concern will be more complicated for the distributed generators (DGs) in dc MGs considering both economic efficiency and plug-and-play performance. In this article, an autonomous finite-time backstepping controller (FTBC) for decentralized economic power dispatch and precise dc-bus voltage regulation of a dc MG is proposed. The high-order nonlinear disturbance observer (HONDO) technique is adopted to estimate the power exchanges between the DGs and loads. So that the decentralized economic power dispatch and rapid voltage regulation can be achieved without any extra output current sensors. In addition, the use of HONDO improves the system's dynamic performance by estimating the disturbances and system uncertainties, and the FTBC guarantees the bus voltage tightly tracking within a finite-time convergence. A rigorous stability analysis is performed to prove the large-signal stability of the regulated system, and some simulations and experiments are carried out.