 The Prussian blue and polypyrrole nanocomposite (PB–PPy) was synthesised by a facile spontaneous self-assembly (SA) procedure through the layering of multiple sequential absorptions of FeCl3–K3[Fe(CN)6] and pyrrole. The morphology of PB–PPy nanocomposite was rough and irregular, whereas the PB nanocubes (used as experimental control) had a diameter of about 40 nm which were formed using the SA method. The intercalation pseudocapacitive mechanism occurs when potassium ions were inserted to the PB framework. The electrochemical behaviour and areal capacitance of PB–PPy were compared with pristine PB. The “knee frequency” was only present in the Nyquist plot of PB–PPy. The result revealed that the PPy significantly improved the capacitance of pristine PB and this made PB–PPy as a promising candidate for supercapacitors. The specific areal capacitance of PB–PPy was at least ten times higher than pristine PB.