In this paper, we report a simple but novel aqueous solution based 'one-pot' method for preparation of (Ni0.65Zn0.35Fe2O4)x-(BaFe12O19)1-x nanocomposites consisting of hard ferrite-soft ferrite phases. Nanocomposites, having same compositions, have also been prepared by employing a physical mixing method. X-ray diffraction analysis showed the presence of nanocrystalline Ni0.65Zn0.35Fe2O4 and BaFe12O19 phases in the composites, prepared by both methods. However, transmission electron microscopic and scanning electron microscopic analysis revealed that, nanocomposites, prepared by one-pot method, possessed better homogeneous intimacy of Ni0.65Zn0.35Fe2O4 and BaFe12O19 phases than that of the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, have shown magnetically single phase behaviour with good spring exchange coupling interaction between hard and soft ferrite phases. These composites possessed enhanced magnetic properties with high saturation magnetization as well as high coercivity. These nanocomposites also exhibited very good microwave absorption properties in the X-band region. Composite having composition (Ni0.65Zn0.35Fe2O4)0.85-(BaFe12O19)0.15 showed the minimum reflection loss of ~-21dB (>99% absorption) at 9.86GHz for absorber thickness of 3.05mm. Magnetic and microwave absorption properties of the nanocomposites, prepared by one-pot method, were found be superior to those of the nanocomposites prepared by physical mixing method as well as pure Ni0.65Zn0.35Fe2O4 and BaFe12O19 nanoparticles. © 2015 Elsevier B.V.