In this study, an aluminium fumarate (AlFum)-based metal-organic framework (MOF) was synthesized via a sustainable aqueous-phase method and functionalized with humic acid (HA) for the removal of the antibiotic doxycycline (Dox) from water. The structural, morphological, and surface characteristics were characterized using FTIR, XRD, BET, and SEM-EDX analyses. The HA-incorporated composite (HA@AlFum) exhibited a markedly higher adsorption capacity than pure AlFum, attributable to its enhanced surface functionality, active site density, surface energy, and specific surface area. Adsorption behaviour was comprehensively evaluated using isotherm, kinetic, and thermodynamic models; the Langmuir isotherm provided the best fit for HA@AlFum, with a maximum monolayer adsorption capacity of 194.38 mg g-1. The equilibrium process times were determined as 120 and 90 min for AlFum and HA@AlFum, respectively. The pseudo-second-order kinetic model exhibited excellent agreement with the HA@AlFum data, indicating that the adsorption mechanism was predominantly governed by physical and chemical interactions (electrostatic interactions, hydrogen bonding and pi-pi electron donor-acceptor (EDA) interactions). HA@AlFum maintained high structural stability, retaining 55.64 % of its adsorption efficiency even after five cycles. These findings highlight the potential of HAfunctionalized AlFum as a highly efficient, rapidly equilibrating, reusable, and sustainable adsorbent for Dox removal.