The presence of drug residue compounds such as antibiotics in the aquatic environment is an enhancing concern due to their toxicity and resistance of these pollutants. The fabrication of new eco-friendly catalyst and simple method for removal of antibiotics in water remediation has become an important challenge. In this work, we show that nanostructured SnFe₂O₄ decorated on bentonite could be conducted as an impressive catalyst in degradation of amoxycillin (AMX) from water under UV light irradiation. The prepared SnFe₂O₄/bentonite was instrumentally characterised using different techniques. The average particle sizes for the SnFe₂O₄ nanoparticles and SnFe₂O₄/bentonite nanocomposites were 45.00 and 51.00 nm, respectively. It can be seen that the pure SnFe₂O₄ nanoparticles and SnFe₂O₄/bentonite nanocomposites have a band gap of about 2.37 eV and 2.08 eV, respectively. The active surface of the SnFe₂O₄/bentonite nanocomposites increases due to the presence of bentonite. The AMX was degraded after 40 min using the SnFe₂O₄/bentonite nanocomposites about 98.00%. The SnFe₂O₄ nanoparticles show the lowest photocatalytic activity (77.4%) compared to the composite sample. The order roles of active species in the AMX degradation were as follows: •O₂⁻ > •OH > e⁻ > h⁺. The operational functions including pH of solution, reaction time and catalyst dosage that influence the degradation were optimised. The statistical optimisation was performed using Box–Behnken design of response surface methodology. The best AMX degradation (98.0%) was observed at pH: 5.00 with 0.500 g/L of SnFe₂O₄/bentonite nanocomposites in 40 min under UV light irradiation. At acidic pH, the catalyst has a negative charge and amoxycillin has a positive charge, and, hence, the degradation is completed on the catalyst surface. Validation model of this process shows the negligible difference response and was 97.62% at this condition.