The breakage and fracture of archaeological potteries not only make them in a dangerous state for a long time but also are not conducive to exhibition and utilization. To repair these fragmentized potteries, it is imperative to synthesize an adhesive that can provide cohesion by bonding the broken surface. In the past decades, organic polymer materials, such as epoxy resin and acrylic resin, have often been used to repair pottery. However, it has been reported that using organic bonding materials for pottery conservation comes with various adverse effects, such as short lifetime, poor compatibility and preservation damage in recent years. With the introduction of material compatibility, the idea of using inorganic materials to protect inorganic cultural relics has been gradually accepted. This study introduces a novel inorganic adhesive, which can achieve excellent bonding performance by using the Al(OH)3–H3PO4 system as base adhesive, CuO as curing agent and nano-TiO2 as filler. To select the optimal base adhesive, the paper investigates the influence of varying weight ratios of H2O–H3PO4 system and Al(OH)3–H3PO4 system on properties such as tensile lap-shear strength, microstructure, high-temperature resistance and phase composition. Moreover, several formulations have been prepared and tested in laboratory to investigate the impact of filler addition on color, bonding performance and surface microstructure. Studies have defined the optimal formulation, and the inorganic phosphate-based adhesive (IPA) has been preliminarily applied to the fractured archaeological pottery. The obtained results demonstrate that the IPA is a promising bonding material and shows great potential in fractured pottery restoration.