Exfoliation of bulk WS2 powder has been conducted by ultrasonication, and its layer by layer peeling is monitored by HRTEM, XRD, UV-Vis, and Raman spectroscopy. HRTEM confirms the peeling process and selected area electron diffraction pattern shows the crystallinity of nanosheets which is in accordance with the X-ray diffraction results. Raman and UV-visible spectroscopies further confirm the exfoliation of WS2 to nanosheets having a few layers. A photodetector developed from a few-layered WS2 film is used for photodetection over wide wavelength and temperature ranges. The detector exhibits the highest sensitivity at 635 nm with a value of 382% at 77 K against a value of 138% at 300 K, while the response and the recovery time are ∼78 ms and ∼40 ms, respectively. Temperature, excitation wavelength, and laser power-dependent studies show the threshold limit of its faithful operation. Temperature-dependent photoresponsivity and sensitivity are explained in terms of the carrier–phonon scattering dependent transport mechanism. The scattering cross-section analysis using the density functional theory model reveals that it is the in-plane and out-of-plane acoustic modes that play a key role in carrier transport, rather than the optical phonons. The influence of atmospheric constituents (N2, O2) on detector performance is checked by a successive exposure to dry N2 and ambient air flow. A 14% reduction in photoresponsivity under O2 exposure is observed and suitable analysis is given in terms of O2 induced enhancement of the electron–hole recombination process, leading to a loss of photogenerated carriers. The sensor's cycling performance remains unaffected even after a prolonged exposure in ambient conditions (55% RH), showing its chemical stability even for long-term use.