Nitric oxide (NO) plays major roles in various physiological processes, such as neurotransmission, vasodilation, blood pressure monitoring, and immune response. Precise regulation of NO concentration in our body can be measured as a potential biomarker for numerous diseases such as hypertension, diabetes, Parkinson’s disease, ischemia, and rheumatoid arthritis. In this report, an electrochemical NO sensor was fabricated using a nanocomposite material consisting of Pt and TiO2 nanoparticles (Pt-TiO2 NPs). Pt and TiO2 nanoparticles were synthesized using the sol–gel method. NO sensing measurements were carried out using a Pt-TiO2 NPs-modified glassy carbon (GC) electrode after adding various concentrations of NO. The nanoparticles-modified GC electrode demonstrated high sensitivity (∼7.81 μA mM–1cm–2) in a wide linear detection range (∼10 nM to 17.79 mM). The sensor exhibited a very low detection limit (∼2.47 nM), high stability, and excellent selectivity toward NO. NO detection using a Pt-TiO2 NPs-deposited screen-printed carbon electrode was also studied in detail. Such a highly sensitive and selective sensor has been employed for noninvasive NO detection in human saliva.