The present work, Pure and zinc doped Iron sulfide (FeS2)/multi-walled carbon nanotubes (MWCNTs) were synthesized via the solvothermal process. The structural, morphological, and textural properties of the as-synthesized nanocomposite were characterized by powder x-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), UV–vis absorption and photoluminescence spectroscopy, and Brunauer–Emmett–Teller (BET). This study aimed at exploring the effectiveness of Zn-FeS2/MWCNTs nanocomposites in the degradation of methylene blue dye under UV-light. The crystallite size of FeS2 was estimated as 25.1 nm. The specific surface area of FeS2 QDs, FeS2/MWCNTs, Zn-FeS2/MWCNTs (1:1) are 47.245, 234.591 and 282.211 m2 g−1, respectively. The photo-activity towards the decomposition of methylene blue with high removal was found within 40 min in acidic medium (pH = 3.5). The novel Zinc doped FeS2/MWCNTs nanocomposites has an excellent potential photo-degradation of organic compound in wastewater.