Pharmaceutical contamination by non-steroidal anti-inflammatory drugs (NSAIDs), like ketoprofen, poses serious environmental concerns due to their persistence and ecotoxic effects. Conventional adsorbents, such as activated carbon and metal-organic frameworks, suffer from high operational costs and limited reusability. This challenge highlights the need to develop sustainable and more efficient alternative adsorbents. This study develops a GO-L-cysteine-gelatin-chitosan composite hydrogel via controlled multi-step crosslinking using EDC/NHS chemistry and freeze-drying, supported by SEM, XRD, and zeta potential analysis. The adsorption performance of the hydrogel for ketoprofen was systematically evaluated across different pH levels, initial drug concentrations, adsorbent dosages, and temperatures. An adsorption efficiency of around 80% was achieved at pH 3 with a 50 ppm ketoprofen solution and 20 mg hydrogel, and exothermic behaviour indicated non-covalent binding via hydrogen bonding, electrostatic interactions and hydrophobic interactions. A dosage study revealed that a minimal dose of 5 mg was sufficient to achieve substantial removal, underscoring the hydrogel’s high binding site availability and efficiency. Temperature-controlled experiments demonstrated increased adsorption at lower temperatures, further supporting the exothermic adsorption pathway. The hydrogel’s robustness, multifunctionality, and superior pharmaceutical removal make it a highly sustainable adsorbent for water treatment.