Adsorption using metal–organic structures is one of the methods of eliminating antibiotics that has shown promising results so far. In this study, to remove the antibiotic cephalexin from water, metal–organic structure MIL-101(Fe) was used. After making the adsorbent, adsorption tests were carried out to remove cephalexin from the aqueous solution in batch mode. The effect of parameters, including initial adsorbent dosage, initial cephalexin concentration, pH, time, and temperature on the adsorption was investigated. Kinetic data showed that the cephalexin adsorption on MIL-101(Fe) followed the pseudo-second-order model. The cephalexin adsorption isotherm was consistent with Langmuir model, and the maximum absorption capacity at 45 °C was 16.44 mg/g. The thermodynamic parameters showed that the cephalexin adsorption on adsorbent is spontaneous, endothermic, and accompanied by an increase in entropy. Therefore, MIL-101(Fe) can be a promising adsorbent to remove cephalexin from aqueous solutions.