Heteroatom doping is an effective way to modulate the electronic structure and properties of graphene. Despite a growing interest in sulfur (S)-doped graphene (SG), synthesis of high-quality SG at low cost remains a great challenge. In this study, we developed a rapid, efficient and cost-effective microwave-assisted solvothermal (MAS) method for the preparation of SG. It was found that a short MAS time of 6min could generate few-layer SG (0.5μm in lateral size) having effective oxygen reduction, high level of S-doping, sole thiophene-S bonding configuration, and high electrical conductivity. Furthermore, the resulting SG could serve as an effective electrocatalyst for H2O2 reduction, showing improved electrocatalytic activity over its undoped counterpart and good sensing performances for highly sensitive and selective detection of H2O2, indicating that SG may be a promising candidate for electrochemical sensor applications.