The aim of the research was corona discharge treatment of meta—(mAr) and para—(pAr) aramid fabrics to increase the surface free energy (SFE) and its polar component, without deterioration of the thermal properties. The fabrics were activated by plasma with 41.0, 71.75, and 102.5 J/cm2 energy. The SFE increased from 40.38 to 70.82 mJ/m2 for mAr and from 44.06 to 70.01 mJ/m2 for the pAr fabric, the polar component increased from 15.33 to 34.68 mJ/m2 and from 5.37 to 33.43 mJ/m2, respectively. The differential scanning calorimetry temperatures have changed and ΔHDeg for both fabrics increased. The weight loss is lower by 3.2% and 0.3% for the highest energy, respectively, for mAr and pAr fabrics.