Li- and Mn-rich layered oxides as cathode materials attract considerable academic and industrial research attention, owing to the superior specific capacity and energy density. The relatively low rate capability is one of the major problems that need to be resolved for these materials. In this work, 0.3Li2MnO3•0.7LiNi1/3Co1/3Mn1/3O2/reduced graphene oxide (LMROs/rGO) is rationally constructed via in-situ thermally reduction method in air flow. This method can reduce graphene oxide availably and meanwhile prevent the reduction of transition element including Ni, Mn and Co in LMROs through typical thermal reduction in inert atmosphere and the aggregation of graphene during chemical reduction process. LMROs/rGO shows enhanced electrical conductivity at polarization potentials of 0.2 V and 4.5 V and lower charge-transfer resistance, in comparison with LMROs, benefited from the addition of conductive rGO with promoted electron transport kinetics. Consequently, LMROs/rGO exhibits high initial capacity of 295.7 mA h−1 at 20 mA g−1 and better rate capability as high as 154.3 mA h g−1 at 500 mA g−1 under 2.0–4.8 V vs. Li/Li+, superior to those of LMROs. Considering the facility and availability of this hybrid/reduction method and needless any reducing agent and additives, it is believed that this simple and scalable in-situ thermal reduction of GO in air flow is an effective approach for the introduction of rGO to either xLi2MnO3∙(1−x)LiMO2 cathode material or other electrode materials which demand a highly oxidative environment for enhanced electrochemical performances.