The low-temperature sintering behavior of Pb(Zr0.53, Ti0.47)O3–Sr(K0.25, Nb0.75)O3 (PZT–SKN) piezoelectric ceramics with LiBiO2 and CuO addition has been investigated. The addition of 6 wt% LiBiO2 or 1 wt% LiBiO2+1 wt% CuO promotes the sinterability of 0.98PZT–0.02SKN ceramics owing to the generation of a liquid phase, resulting in a reduction of sintering temperature by about 300°–350°C. The microstructure, dielectric, and piezoelectric properties of flux-sintered ceramics were examined and compared with materials conventionally sintered at 1250°C. PZT–SKN ceramics with 1 wt% LiBiO2+1 wt% CuO addition were sintered to high density at 900°C for 1 h. The resulting samples exhibited a high-field d33 piezoelectric coefficient of 415 pm/V with a Curie temperature Tc of around 351°C, dielectric constant ɛr of 1235, and planar coupling factor kp of 0.54. The reduced sintering temperature and short soaking time, together with the favorable dielectric and piezoelectric properties of the fluxed PZT–SKN ceramics, demonstrate the potential opportunity of integration with low-temperature cofired ceramic materials and low-fire electrode materials for the multilayer piezoelectric transducer application.