© 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Due to their environmental friendliness, strong remediation capabilities, and low cost, biochar sorbents have garnered considerable attention recently. In the current study, the effectiveness of fish scale biochar (FSBC) as an alternative material in eliminating toxic cadmium (Cd2+) ions from contaminated water was examined using batch and fixed-bed experiments for the first time. The impact of major design parameters on biosorption performance, such as solution pH, contact time, biochar quantity, and flow rate was investigated. The pseudo-second-order kinetic and Langmuir isotherm models were the best models for the biosorption process. Maximum monolayer uptake capacity and removal efficiency in batch mode were determined to be 99.14 mg g−1 and 95.40%, respectively. Under dynamic flow conditions, the proposed biochar also demonstrated a high Cd2+ removal efficiency (99.02%). Consecutive biosorption/desorption potential was evaluated via an EDTA elution to determine the suitability of the FSBC for long-term utilization. After ten cycles, the final biosorption and recovery efficiencies of FSBC were higher than 78 and 99%, respectively. According to FTIR analyses, the –NH, –OH, and carboxyl groups were the major functional sites for Cd2+ ion binding. EDX findings confirm the SEM examination, revealing that FSBC removes the Cd2+ ions effectively. FSBC demonstrates a good ability to remove Cd2+ ions even from the real effluent sample. As a result, a recyclable, low-cost, and effective biochar for the treatment of Cd2+ contamination has been revealed.