The KxWO3 nanosheets consisting of superfine nanowires were successfully synthesized in ambient air. The detailed electron microscopy and X-ray diffraction investigations imply that the nanosheets were obtained by self-assembly of the ordered nanowires with exposed {0110}H facets. The sheet morphology is closely related with the growth conditions including temperature and time, etc. A possible mechanism based on the oriented attachment of neighboring nanowires for the formation of nanosheets is proposed. Our results shed light on the interfacial characteristics of self-assembled KxWO3 nanowires and can serve as guidance to the future design of relevant two-dimensional structures for various electrical and optical applications.