Na0.5Bi0.5TiO3 (NBT) platelets with high aspect ratio were synthesized from Na0.5Bi4.5Ti4O15 (NBIT) precursors via a topochemical microcrystal conversion in molten salt conditions. The effect of the synthesis parameters, such as the molten salt system, synthesis temperature, and the molar ratio of Na2CO3 and NBIT, was investigated. The results showed that NaCl–KCl molten salt environment and excess Na2CO3 played a positive role in the synthesis, square‐shaped NBT was obtained at 950°C in NaCl–KCl molten salt and a TiO2‐free environment, and it was a suitable template candidate to achieve NBT‐based textured ceramics using the reactive template grain growth (RTGG) method.