This paper describes the fabrication of a cost-effective, low-power flexible ammonia sensor that uses few layered molybdenum disulphide (MoS2) nanoflakes as the sensing layer. The nanoflakes were exfoliated using a sonication-assisted liquid exfoliation approach. A thin film of MoS2 was spin coated on a polymethyl methacrylate film, and aluminium electrodes were deposited on the top of the film that was eventually transferred on a polyethylene terephthalate flexible substrate. The response of the sensing layer against various concentrations of ammonia near room temperature was recorded. The sensor showed noticeable response, recovery, and selectivity toward ammonia when tested against various volatile organic compounds. The nanomaterial was further analyzed using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction for examining surface morphology, structure, and composition. Thus, our sensor device holds great potential in the development of a batch-fabricated, sensitive, low-power, cost-effective, and fast ammonia sensor with an application in flexible electronics.