Abstract: To broaden the application prospects of functional Pickering emulsion-based pharmaceutical formulations stabilized by alginate derivatives/organo-montmorillonite (OMT) composites, this work employed an amidation reaction strategy to graft 7-(diethylamino) coumarin-3-carboxylic acid (DCCA) as a hydrophobic functional group onto the alginate backbone via cystamine dihydrochloride, yielding an alginate-grafted coumarin derivative (Alg-g-DCCA) with a degree of substitution of 8.5%. Meanwhile, OMT with good interfacial activity was prepared by wet ball milling using octylphenyl polyoxyethylene ether as an intercalating agent. Subsequently, the Alg-g-DCCA/OMT composites were used as Pickering emulsifiers, and drug-loaded Pickering emulsions stabilized by Alg-g-DCCA synergistically with OMT were fabricated via high-speed shearing, using olive oil dissolving β-carotene as the oil phase. The distribution of the Alg-g-DCCA/OMT composites at the oil-water interface and their emulsification mechanism were investigated, and the effects of different OMT concentrations on the stability and viscoelasticity of the Pickering emulsions synergistically stabilized by Alg-g-DCCA/OMT were explored. On this basis, the encapsulation efficiency and release properties of the Pickering emulsions for hydrophobic drug, β-carotene, were further validated. The results indicated that Alg-g-DCCA and OMT were associated via hydrogen bonding formed between the carboxyl/amide groups on the Alg-g-DCCA molecule chain and the silanol groups on the surface of OMT. At an OMT concentration of 0.5% (w/v), they formed composite soft particles with a diameter of approximately 317.2 nm and a zeta potential of -33.8 mV, exhibiting favorable suspension stability and interfacial activity. Moreover, the Alg-g-DCCA/OMT composite particles could form a stable adsorption layer at the oil-water interface, effectively inhibiting droplet coalescence and creaming. SEM observations further revealed that at 0.5% (w/v) OMT, the composite particles formed a dense and ordered particle film on the oil droplet surface, whereas excessive OMT led to incomplete interfacial coverage. Rheological tests demonstrated that an appropriate OMT concentration enabled the composite particles to form a robust interfacial film at the oil-water interface and to construct a three-dimensional network structure in the continuous phase, endowing the Pickering emulsions with excellent viscoelasticity and resistance to gravity-induced creaming. Drug release experiments showed that the drug-loaded Pickering emulsions exhibited significantly inhibited release under acidic conditions (pH 1.2), displaying pH-responsive sustained-release characteristics. Collectively, these results demonstrate that there exists an optimal concentration ratio of Alg-g-DCCA to OMT for synergistic stabilization of Pickering emulsions, enabling efficient loading and controlled release of hydrophobic drugs.