With the bidirectional power flow provided by the Energy Internet, various methods are promoted to improve and increase the energy utilization between Energy Internet and main grid (MG). This paper proposes a novel distributed coordinated controller combined with a multiagent-based consensus algorithm, which is applied to distributed generators in the Energy Internet. Then, the decomposed tasks, models, and information flow of the proposed method are analyzed. The proposed coordinated controller installed between the Energy Internet and MG keeps voltage angles and amplitudes consensus, while providing accurate power-sharing and minimizing circulating currents. Finally, the Energy Internet can be integrated into the MG seamlessly if necessary. Hence, the Energy Internet can be operated as a spinning reserve system. Simulation results are provided to show the effectiveness of the proposed controller in an Energy Internet.