Abstract A novel distributed fixed-time control system is proposed to optimize the power allocation for DC multi-microgrids (MGs). In which, MG-control and cluster-control layers are proposed to handle the economic operation in a fixed-time manner for individual MGs and multi-MGs, respectively. In each MG, the primary and the secondary controllers match DGs’ incremental costs (ICs) as well as restore MG’s average voltage, within a fixed time regardless of the initial conditions, to guarantee the optimal load dispatch while considering line losses, generation-demand power balance and DGs’ generation limits. For the multi-MGs, the distributed tertiary controllers optimize the power flow between MGs by adjusting their voltages references to achieve the minimum global total production cost. The developed controller is distinguished with its accelerated convergence rate independent of the initial states as compared to the existing works. The efficacy of the proposed controller is proven by rigorous analysis and verified by comprehensive simulation, and experimental results.