Dissolved organic matter (DOM) removal from saline water is essential for producing potable water, yet conventional activated carbon is costly and often derived from non-renewable precursors. This study evaluates water hyacinth leaves (WHL) as a waste-biomass biosorbent and coal-based graphite (GR) as a carbon adsorbent for DOM removal from saline water containing sodium chloride (NaCl) and magnesium chloride (MgCl₂). DOM was extracted from potting soil (initial dissolved organic carbon ≈ 19–34 mg L⁻¹), and batch experiments were conducted over a salinity range of 0–45 g L⁻¹ to assess the effects of salt type, contact time, adsorbent dosage, DOM concentration, and temperature. Characterization (BET, SEM-EDS, FTIR, XRD) showed that WHL is a micro-mesoporous, chemically active biomass with abundant oxygen-containing functional groups, whereas GR is a meso-macroporous, highly crystalline carbon with fewer surface functionalities but larger pore volume. GR achieved consistently high DOM removal (>80%) for all NaCl and MgCl₂ concentrations, with a maximum of about 90% at 1 g L⁻¹ and 35 g L⁻¹ NaCl, indicating robust, salt-tolerant adsorption. WHL performance decreased from approximately 75–80% DOM removal at low salinity to below 50% at the highest MgCl₂ concentration, suggesting stronger ionic competition and active-site blockage by divalent cations. Adsorption kinetics for both adsorbents followed the pseudo-second-order model (R² > 0.98), and equilibrium data were best described by the Freundlich isotherm, with GR exhibiting more favorable 1/n values. Overall, GR is more suitable for DOM removal from saline waters, while WHL is better suited to low-salinity applications. © 2026 The Authors.