The stabilizing effect of biopolymers on Pickering emulsions has attracted widespread interest in recent years. In this study, the interactions between chitosan (CS) and octenyl succinic anhydride starch (OS) were investigated and used to modulate the interfacial properties of Pickering emulsions, which are crucial for determining emulsion stability. CS/OS complex particles were prepared via electrostatic and hydrogen-bonding interactions and used to stabilize Pickering emulsions for the encapsulation of astaxanthin (AST). The three-phase contact angle and confocal laser microscopy results indicated that the CS/OS particles could reduce the oil-water interfacial tension and provide a stable interface layer. The loss rate of AST in CS/OS-stabilized Pickering emulsions (31.25 %) was significantly lower than that of Tween 80-stabilized emulsions (49.50 %) after storage at 37 °C for 60 days. The bioaccessibility of AST in the CS/OS-stabilized Pickering emulsions (61.38 %) was twice that in the Tween 80-stabilized emulsions (28.30 %). Moreover, CS/OS-stabilized Pickering emulsions effectively masked the undesirable algal odor of AST. The emulsions exhibited textural and rheological properties similar to those of salad dressings, suggesting their potential as substitutes for salad dressings. These findings provide novel insights into the utilization of efficient AST delivery systems.