Metal-free photocatalysts with excellent visible-light absorption and highly efficient photocatalytic activity are attractive in the field of photocatalysis owing to their environmental friendliness. Black phosphorus (BP) shows a great potential in photoelectric conversion and photocatalysis due to its tunable band gap and two-dimensional structure. In this work, a stabilized metal-free photocatalyst, reduced graphene oxide (rGO)-wrapped BP heterostructure, was prepared by assembling BP and GO nanosheets in aqueous solution followed by partial reduction and lyophilization. The surface tension of the partially reduced GO during lyophilization could make rGO nanosheets tightly wrap on both surfaces of exfoliated BP nanosheets. This wrapped heterostructure with tight bonding between rGO and BP nanosheets led to a high photocatalytic activity, owing to the rapid transfer of the photogenerated electron-hole pairs at the rGO/BP heterojunction and the high stability of rGO protecting BP from oxygen attack. This work not only provided a general method to prepare the sandwiched heterojunction based on GO with good interface binding capability but also constructed a highly active, stable, metal-free photocatalyst based on BP.