Mildly oxidized graphene oxide (MOGO) was achieved by chemical exfoliation of graphite through a modified Hummers' method. The MOGO is not only able to be stably dispersed in water at a high concentration (1 mg mL⁻¹), but also preserves the highly crystalline structure of the conjugated carbon framework. Thus, the MOGO can be used as a low-defect precursor to prepare highly conductive graphene by chemical reduction. The electrical conductivity of hydrazine or hydriodic acid reduced MOGO was measured to be 169 or 405 S cm⁻¹. This value is about 3 times that of the chemically converted graphene (CCG) prepared by reducing the conventional graphene oxide via Hummers' method with the same reducing agent. This work not only develops a facile route to high-throughput preparation of processable high-quality CCG, but also provides a deeper understanding of the crucial influence of the degree of oxidation of graphene oxide on the electrical properties of its reduced product.