In the present work, we prepared electrospun polyacrylonitrile (PAN)/ cobalt sulfide (CoS) nanocomposite membranes by encapsulating different weight percentage (1, 2, and 3wt%) of CoS nanoparticles in PAN nanofibers for dye-sensitized solar cells (DSSCs). The electrospun PAN/CoS nanocomposite membranes (esCPMs) were activated by immersing in an ionic liquid electrolyte containing 0.5M LiI, 0.05M I-2, 0.5M 4-tert butylpyridine and0.5M 1-butyl-3-methylimidazolium iodide in acetonitrile to obtain their corresponding nanocomposite membrane electrolytes (esCPMEs). The influences of CoS content on the physical and electrochemical properties of esPM were investigated. The addition of CoS nanoparticles reduced the degree of partial crystallinity of esPM to an amorphous state. An electrochemical impedance and Tafel polarization measurements revealed that the esCPME has high electrocatalytic activity with enhanced ionic conductivity. The 2wt% CoS encapsulated esCPME ensured the effective charge transfer at the electrode/electrolyte interface with the lower electron recombination rate in DSSC, which ultimately increased the photoconversion efficiency (7.41%) at an incident light intensity of 100mWcm(-2).