0–3 type ferroelectric–phosphor composite ceramics cannot be prepared by the traditional solid-state sintering (SSS) method due to the strong chemical reaction between ferroelectrics and phosphors during high-temperature sintering. The cold sintering process (CSP) may solve this issue by densifying ceramics at ultralow sintering temperatures. In this work, dense 0–3 type 0.8BaTiO₃–0.2CaTiO₃:Pr³⁺ (0.8BT–0.2CT:Pr³⁺) binary composite ceramics were fabricated at an ultralow temperature of 225 °C via CSP with the Ba(OH)₂·8H₂O hydrated flux. The effects of the Ba(OH)₂·8H₂O content, sintering temperature, and sintering time on the microstructure and densification of the ceramics were investigated. The density of the composite ceramics prepared by the optimized sintering parameters reaches 89%. Both energy-dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) confirm the existence of BT and CT:Pr³⁺ phases in the prepared ceramics. A strong ferroelectric performance is obtained, and the luminescent properties of CT:Pr³⁺ are preserved for the ceramics. Furthermore, the 0.8BT–0.2CT:Pr³⁺ composite ceramics prepared by CSP have stronger photoluminescence and photo-stimulated luminescence than their counterparts prepared by cold sintering assistance (CSA) and SSS methods. Therefore, CSP is a promising method for combining luminescent and ferroelectric properties into 0–3 type composite ceramics.