In recent years, the buildup of antibiotic residues in freshwater and wastewater systems has become a significant environmental problem. The fluorinated quinolone-based drug ciprofloxacin (CIP) is a persistent organic pollutant in freshwater and wastewater streams with broad spectrum antibacterial action. Prosopis juliflora is an environmentally invasive weed that has invaded India’s thousands of hectares of land. In the present investigation, Prosopis juliflora biochar (PJB) was prepared by pyrolysis at a temperature of 550 °C under inert conditions, and the prepared biochar was activated with ZnCl2. The adsorption data of CIP onto synthesized activated biochar was then examined by fitting to adsorption isotherm and kinetic models. The effects of different adsorption parameters (pH, adsorbent dosage, temperature, and initial CIP concentration) were investigated. Prepared PJB-AC had a specific surface area of 360.5 m2/g. The isotherm model fitting results showed that the PJB-AC exhibited a comparable adsorption performance (158.2 mg/g) compared to commercially available activated carbon (147.5 mg/g) towards CIP removal. Kinetic regression results showed that the CIP adsorption was well described by a pseudo-second-order kinetic model indicating chemical adsorption of CIP. This is the first study that reported on understanding the adsorption characteristics of various forms of Prosopis julifora biomass (PJ, PJB, and PJB-AC) on CIP removal from aqueous solutions. The results from this study indicate that PJB-AC is a promising adsorbent for CIP removal. Graphical Abstract: [Figure not available: see fulltext.]