Wells-Dawson type cobalt-based Polyoxometalate (Co-POM) was deposited over carbon nanotube (CNTs) fiber and employed as an electrochemical sensor for the detection of glucose and ascorbic acid in basic media. Surface morphology and elemental composition of the developed electrode was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). SEM images verified the homogenous covering of Co-POM over the surface of CNTs fiber. Electrochemical response of fabricated electrode was investigated via cyclic voltammetry and chronoamperometry in 0.1 M KOH solution. Electro-oxidation of glucose showed high sensitivity of 1000 µAmM-1cm−2, low limit of detection 0.42 µM and broad linear range of up to 23 mM with short response time of about 4 s. Furthermore, the fabricated electrode showed boosted sensing performance for ascorbic acid with a sensitivity of 300 µAmM-1cm−2, detection limit of 0.10 µM and 10 mM linear range with a response time of 5 s.