<p>We have effectively developed a strategy to significantly alter the nonlinear SA (SA) behavior and achieve a transition from negative to positive photoresponse (NPR to PPR) in nanocomposite films (NCFs) composed of Molybdenum disulfide (MoS₂), ZnS, and poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT: PSS). This was achieved by controlling the concentration of ZnS. Different concentrations of ZnS are introduced into NCF to create films using a straightforward drop-casting procedure on the glass substrate. The refractive index (n) and extinction coefficient (k) of the fabricated NCFs were determined through analysis based on the Kramers-Kronig relations. Nonlinear optical studies indicate significant changes in the optical nonlinearity of pristine PEDOT: PSS when combined with MoS₂ and ZnS. In particular, the ZnS/MoS₂/PEDOT: PSS NCFs exhibit evidence of Pauli blocking, which contributes to an enhanced SA response within the composite system. It also noted a NPR to UV light exposure. This unique response is linked to the trapping and confinement of charges generated by the radiation. These results underscore the pronounced Saturable Absorption (SA) behavior and NPR, indicating strong potential for advancing research into the photoresponsive and nonlinear optical properties of NCFs.</p>