BaTiO3 particle/polyvinylbutyral composite films were synthesized from titanium-organics and barium ions in aqueous solution using a direct current (dc) field. Titanium-organic films on stainless substrates were reacted with barium nitrate solution under dc field. BaTiO3 nanoparticles were formed in the precursor film at temperatures as low as 30 °C at atmospheric pressure. The crystallization of BaTiO3 particles was dependent on the synthetic conditions, such as applied field, reaction time, and temperature. Crystalline BaTiO3 particles were synthesized in the polymer matrix at 2.3 V/cm and 50 °C for 2 h. The absorption edge of BaTiO3 particle/polyvinylbutyral composite was 343 nm and was blue-shifted compared with that of micron-sized BaTiO3.