<p>Hexavalent chromium removal from the environment remains a crucial worldwide challenge. Microbiological approaches are among the straightforward strategies that rely mainly on the bacteria's survival mechanisms upon exposure to toxic metals, such as biosorption. This study evaluated the biosorption potential of both free and immobilized cells of <i>Bacillus paramycoides</i> for the removal of chromium from electroplating wastewater. The free cell system achieved a removal efficiency of 85.25% after 48 h of incubation. Immobilized cells, which were entrapped within a natural loofah sponge matrix, achieved a slightly higher biosorption efficiency of 88.01%, highlighting the effectiveness of loofah as a low-cost, biodegradable immobilization carrier. Adsorption isotherm analysis indicated that the Langmuir model provided the best fit (highest R²), indicating monolayer adsorption on a homogeneous surface. The Freundlich isotherm exhibited a lower R² value, suggesting that it was less suitable for explaining the biosorption behavior under the tested conditions. Kinetic modelling further revealed that the pseudo-second-order model best described the biosorption process, pointing the chemisorption as the dominant mechanism. Scanning electron microscopy images revealed that bacterial cells exposed to chromium had higher surface roughness, deformation, and particle deposition, with more noticeable effects in immobilized systems. The active activities of hydroxyl, amino, and carboxyl groups in chromium binding were confirmed by Fourier-transform infrared spectroscopy, which showed changes in these groups. Both free and immobilized <i>Bacillus paramycoides</i> showed great promise for environmentally safe and effective wastewater treatment of Cr(VI) contamination, with immobilization providing a marginal performance advantage.</p>