The metallic (1T) transition metal dichalcogenides (TMDCs) are known for their superior electrocatalytic performance, due to their high conductivity, active basal-planes, and exposed edges. Our novel approach of coupling a metallic-NiTe₂/Ni nano-skeleton with 1T-Co-WS₂ nanosheet in a core–shell arrangement to develop a hybrid heterostructure (1T Co-WS₂/NiTe₂/Ni) has helped to outperform the trifunctional-electrocatalytic activity (HER, OER, and ORR). 1T-Co-WS₂/NiTe₂/Ni only requires ultralow overpotential (η_HER = 88 mV@10, η_OER = 290 mV@30), higher half-wave potential for ORR (E_1/2 = 0.781 V vs RHE), small Tafel slopes (HER = 68 mV dec^-1, OER = 98 mV dec^-1, and ORR = 63 mV dec^-1) with high electrocatalytic surface area and robust stability in corresponding half-cell reactions. The designed heterostructured electrocatalyst (1T Co-WS₂/NiTe₂/Ni) presented exceptional total water-splitting performance, requiring a low voltage of 1.521 V to yield 10 mA cm⁻² current with extensive structural and electrochemical durability. Such performance could be attributed towards improved nanochannel morphology with exposed active edge, fluent electrode-kinetics, facile adsorption–desorption of reaction intermediates owing to the intrinsically tuned 1T-WS₂ by cobalt-doping, and hybridized NiTe₂/Ni nano-skeleton. The DFT study confirmed that the incorporation of Co atoms in basal plane and the edge sites of WS₂ lattice induces the redistribution and modulation of electronic structure for fast electron/charge transfer and the synergistic coupling of 1T NiTe₂ heterostructures bolstered the electrocatalytic activity of the as-prepared catalysts. These outcomes provide a prospect towards the design and application of efficient 2D/2D heterostructured electrocatalyst for zero emission energy goal.