A low cost, sensitive and efficient ascorbic acid (AA) sensor was developed using a molybdenum oxide (MoOx) and Prussian Blue (PB) nanocomposite, anchored on a graphite felt (GF) substrate (MoOx@PB/GF). MoO2 nanorods, which were fabricated by annealing of Mo-precursor, play a key role in promoting the synthesis of PB from Fe3+ and [Fe(CN)6]3-. The as-prepared electrode was characterized by scanning electronmicroscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and electrochemical methods. The modified electrode exhibited outstanding performances for the electrocatalytic oxidation of AA, with a sensitivity as high as 0.37 A/M, a good linear response in a concentration range from 0.0125 μM to 293 μM, an ultra-low detection limit of 0.0119 μM (S/N = 3), as well as a notable reproducibility and an excellent selectivity. Finally, the composite electrode gave satisfactory results for practical sample analyses, e.g. standard AA added in drinking water.