Polydopamine (PDA) is the most typical kind of synthetic melanin, which possesses interesting properties such as antioxidation, photoprotection, metal chelation, and energy dissipation. Over the past few years, PDA has been successfully synthesized via polymerization methods and has demonstrated excellent free radical scavenging ability. The related applications have been rapidly expanded to include sunscreens, anti-inflammatory treatment, and composite material fabrication. Despite great progress, the comprehensive mechanisms of its free radical scavenging behaviors are not fully understood. This article strives to summarize the possible mechanisms, established antioxidant regulation methods and the related biomedical applications of PDA free radical scavengers. We believe this paper can provide insight into the current PDA scavenging systems and offer inspiration towards the design of new melanin-inspired scavengers with a broad range of biomedical applications.