This study presents a novel thermal control coating based on the thermochromic properties of K-doped manganite nanoparticles. The nanoparticles, with a size distribution of 100–200 nm, were dispersed into a polymer matrix and cured below 200°C. The phase transition of the nanoparticles was observed from ferromagnetic metallic to paramagnetic insulator states, with the phase transition temperature increasing with higher K doping levels. Coatings with and without pore defects were prepared using different polymer matrices, showing a sharp variation in emittance with increasing temperature. The emittance variation magnitude reached up to 0.46, making it suitable for space thermal control applications. The study suggests that a pigment content of 50 wt% is sufficient to achieve a large emittance variation. The research highlights the potential of K-doped manganite coatings for intelligent thermochromic devices in modern spacecraft thermal control.This study presents a novel thermal control coating based on the thermochromic properties of K-doped manganite nanoparticles. The nanoparticles, with a size distribution of 100–200 nm, were dispersed into a polymer matrix and cured below 200°C. The phase transition of the nanoparticles was observed from ferromagnetic metallic to paramagnetic insulator states, with the phase transition temperature increasing with higher K doping levels. Coatings with and without pore defects were prepared using different polymer matrices, showing a sharp variation in emittance with increasing temperature. The emittance variation magnitude reached up to 0.46, making it suitable for space thermal control applications. The study suggests that a pigment content of 50 wt% is sufficient to achieve a large emittance variation. The research highlights the potential of K-doped manganite coatings for intelligent thermochromic devices in modern spacecraft thermal control.