Graphene oxide–bacterial cellulose (GO/BC) nanocomposite hydrogels with well‐dispersed GO in the network of BC are successfully developed using a facile one‐step in situ biosynthesis by adding GO suspension into the culture medium of BC. During the biosynthesis process, the crystallinity index of BC decreases and GO is partially reduced. The experimental results indicate that GO nanosheets are uniformly dispersed and well‐bound to the BC matrix and that the 3D porous structure of BC is sustained. This is responsible for efficient load transfer between the GO reinforcement and BC matrix. Compared with the pure BC, the tensile strength and Young's modulus of the GO/BC nanocomposite hydrogel containing 0.48 wt% GO are significantly improved by about 38 and 120%, respectively. The GO/BC nanocomposite hydrogels are promising as a new material for tissue engineering scaffolds. Graphene oxide–bacterial cellulose (GO/BC) nanocomposite hydrogels with well‐dispersed GO in the network of BC have been successfully developed using a facile one‐step in situ biosynthesis by adding GO suspension into the culture medium of BC. The composites show a significant increase in tensile properties at relatively low GO loadings.