The structure–activity-durability relationship of Pt nanoclusters anchored on aminoclay functionalized multi-walled carbon nanotube (Pt/AC-MWCNT) was well corroborated by the correlation between physicochemical properties and electrocatalytic oxygen-reduction (ORR) and methanol oxidation reactions. By TEM and XRD results, the closely-packed small Pt nanoparticles (~2 nm) forming an unique spherical-shaped nanocluster morphology with higher lattice strain (-0.432%) were determined. The dual functionality of Pt/AC-MWCNT has been substantially confirmed from the key electrochemical parameters of mass and specific activities for both ORR (0.223 mA μg−1 and 0.4 mA cm−2) and MOR (1688.8 mA mg−1 and 3.03 mA cm−2). After the accelerated durability test, the higher retention percentage of its initial catalytic activity for both ORR (5000 cycles) and MOR (2000 cycles) confirms the sustained stability of the catalyst. The superior performance of Pt/AC-MWCNT was attributed to, (i) the synergistic effect between Pt nanoclusters and hybrid support, (ii) the electronic effect by compressive lattice strain, and (iii) the shape of Pt nanocluster with tiny particles. Compared to commercial Pt/C (Alfa Aesar) and reported Pt-based nanostructures for ORR and MOR, the Pt/AC-MWNCT has shown promising dual-functional electrocatalytic efficiency.