AbstractIn this work, a series of BaTi1−xMnxO3–polyimide films were prepared by simple solution casting method. For the preparation of composite films firstly, manganese doped barium titanate, BaTi1−xMnxO3 (where x = 0.00, 0.01, 0.03, 0.05) was synthesized by sol‐gel process. The effect of Mn doping on its structural and dielectric properties was nicely explained. The highest dielectric constant value of 7,104 was obtained for BaTi0.99Mn0.01O3 (BTMn) nanoparticles with low dielectric loss value 2.44. It was observed that Mn‐doping concentration on barium titanate influences its crystal structure. Improved dielectric properties were reported for nanocomposite thin films containing BaTi0.99Mn0.01O3 and polyimide (PI). A series of five homogeneous nanocomposite films were successfully prepared and were characterized thoroughly. The dielectric properties were studied as a function of frequency and loading percentage of BTMn in PI. The dielectric constant of the BTMn/PI nanocomposite films increased from 3.23 to 8.63 with the increase in loading percentage of ceramic from 0 to 5 wt%, respectively. The nanocomposite films were flexible with good mechanical properties and the flexibility decreased with increase in loading percentage of BTMn. The films showed high thermal stability in nitrogen atmosphere up to 571°C with 10% weight loss and also exhibited high glass transition temperature up to 337°C.