Access to clean water is essential for human health, yet the persistent and poorly degradable nature of synthetic dyes continues to threaten aquatic environments. This challenge underscores the need for efficient nanoscale photocatalysts capable of enhancing pollutant degradation. In this study, an eco-friendly, simple, and cost-effective pulse laser ablation in liquid (PLAL) technique was employed to synthesize high-purity chromium nanoparticles (CrNPs) without the use of surfactants or chemical precursors. CrNPs were produced at various laser energies and evaluated for their potential in dye-degradation applications. The nanoparticles were characterized using ultraviolet–visible (UV–Vis) spectroscopy, fluorescence (FL) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy to elucidate their optical and chemical properties. UV–Vis and FL analyses showed that laser energy significantly influences NP size distribution and optical behavior, while bandgap analysis revealed a slight shift with increasing laser energy. FTIR spectra confirmed the presence of Cr–O and O–H functional groups, which are known to contribute to photocatalytic activity. The absorption spectra of methylene blue (MB) decreased gradually with irradiation time. Photocatalytic degradation experiments under visible light demonstrated that CrNPs exhibit strong photodegradation efficiency. Overall, these findings highlight the potential of surfactant-free, PLAL-synthesized CrNPs as promising photocatalysts for the remediation of pharmaceutical pollutants and heavy-metal-contaminated wastewater.