Chiral gold nanoparticles (Au NPs) have been investigated widely and have shown great potential in biomedical applications, such as biosensing, combating bacterial infections and tissue regeneration. However, some stabilizers and reducing agents for the synthesis of chiral Au NPs can produce toxicity in living organisms. Therefore, it is interesting to design green methods to prepare chiral gold nanoparticles that are nontoxic, environment-friendly, and low-cost. Herein, novel biocompatible chiral Au NPs with a diameter of 54.4 ± 14.9 nm were prepared by the in situ reduction of HAuCl₄ with alginates as the green reducing agent and chiral-inducing and stabilizing agent. XPS, TGA, UV-Vis and CD analyses demonstrated that alginate-stabilized chiral Au NPs (ALG-Au NPs) were successfully prepared, while biocompatibility assessment showed that cell viability was 116.0% when the concentration of ALG-Au NPs arrived at 300 μg/mL, which indicated that ALG-AuNPs showed excellent biocompatibility. Furthermore, the ALG-Au NPs can respond to metal ions, such as Ca²⁺, Cu²⁺, Mn²⁺ and so on, implying potential application for biosensing.