Dye-sensitized solar cells (DSSCs) have gained recognition as a promising indoor photovoltaic technology, drawing considerable attention for their ability to convert light into electricity. In this study, we present a straightforward one-step hydrothermal synthesis method for producing cobalt sulfide nanoparticles decorated with reduced graphene oxide (CoS2/RGO) nanocomposites, serving as an efficient counter electrode (CE) material for DSSCs. The CoS2/RGO nanocomposites exhibited a chain-like structure formed by RGO nanosheet-decorated spherical particles interconnected with CoS2. Demonstrating excellent electrocatalytic activity with a low Epp (peak-to-peak separation) value, the CoS2/RGO nanocomposites outperformed pristine CoS2 nanoparticles. Moreover, the power conversion efficiency of the CoS2/RGO hybrid structure-based CE surpassed that of the pristine CoS2 nanoparticles. These findings suggest that the facile synthesis of CoS2/RGO nanocomposites holds great promise as an electrode material for effective CEs in DSSC applications. C1 [Manikandan, V. S.; Thirumurugan, Arun] Univ Atacama, Sede Vallenar, Costanera 105, Vallenar 1612178, Chile. [George, Kesiya] Cent Inst Petrochem Engn & Technol CIPET, Sch Adv Res, Lab Adv Res Polymer Mat LARPM, Bhubaneswar 751024, India. [Govindraj, T.; Navaneethan, M.] SRM Inst Sci & Technol, Dept Phys & Nanotechnol, Funct Mat & Energy Devices Lab, Chennai 603203, India. [Prabakaran, K.] KPR Inst Engn & Technol, Dept Phys, Coimbatore 641407, India. [Mangalaraja, R. V.] Univ Adolfo Ibanez, Fac Engn & Sci, Diagonal Torres 2640, Santiago 7941169, Chile. [Mangalaraja, R. V.] Karpagam Acad Higher Educ, Dept Mech Engn, Coimbatore 641021, Tamil Nadu, India. [Navaneethan, M.] SRM Inst Sci & Technol, Nanotechnol Res Ctr NRC, Chennai 603203, India. C3 Universidad de Atacama; SRM Institute of Science & Technology Chennai; Universidad Adolfo Ibanez; Karpagam Academy of Higher Education (KAHE); SRM Institute of Science & Technology Chennai