Synthesis and application of NiO-multiwall carbon nanotube nanocomposite (NiO/MWCNTs) and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) in the carbon paste matrix as high sensitive sensors for voltammetric determination of vitamin C have been reported. The oxidation peak potential of vitamin C at the surface of the ([Bmim]BF4) NiO/MWCNT carbon paste electrode (NiO/MWCNTs/([Bmim]BF4/CPE) appeared at 440mV, which was about 200mV lower than the oxidation peak potential at the surface of the simple carbon paste electrode under a similar condition. Also, the oxidation peak current was increased for about 3.7 times at the surface of NiO/MWCNTs/([Bmim]BF4/CPE compared to carbon paste electrode. At an optimum condition (pH7.0), the two peaks are separated ca. 0.44 and 0.85V for vitamin C and vitamin B9. This point shows that vitamin C can be determined in the presence of vitamin B9. The linear response range and detection limit were found to be 0.1–1000μM and 0.06μM, respectively. The proposed sensor was successfully applied for the determination of vitamin C in food and drug samples.