Developing highly effective photocatalysts is essential in environmental remediation and sustainable manufacturing. In this study, a carbon-based semiconductor nanocomposite (g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>S<inf>3</inf>) was effectively prepared via a hydrothermal approach. Comprehensive physicochemical characterizations were active to assess the morphological, structural, and photochemical attributes of the fabricated g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>S<inf>3</inf> nanocomposites using microscopic and spectrophotometric analyses while the intermediate products formation was assessed through GC-MS analysis. Photocatalytic degradation performance was evaluated against Reactive Black 5 (RB5) and Indigo Carmine (IC) dyes. The g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>S<inf>3</inf> nanocomposites exhibited remarkable photodegradation efficiency compared with pure g-C<inf>3</inf>N<inf>4</inf> and Bi<inf>2</inf>S<inf>3</inf> catalysts, achieving 95.6 % degradation for IC and 97.5 % for RB5 after 120 min of Ultraviolet A irradiation (UVA). This excellent photocatalytic activity demonstrates the potential of g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>S<inf>3</inf> nanocomposites for future employment in visible-light-driven wastewater treatment. The mechanism of g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>S<inf>3</inf> NCs photocatalysis involves efficient charge separation, active site interactions, electron and hole transfer, and subsequent oxidative removal of organic pollutants, revealing the NCs suitability for sustainable environmental applications. Furthermore, the effectiveness of the g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>S<inf>3</inf> nanocomposites in combating Streptococcus mutans and Enterococcus faecalis was appraised under UVA light exposure to determine their antibacterial properties. © 2023 Elsevier B.V., All rights reserved.