ζ-Carotene, a key intermediate in lycopene biosynthesis, is widely found in plants and photosynthetic microorganisms, but its isomer-specific properties remain poorly understood due to isolation and purification challenges. Researchers have now developed a purification strategy to obtain high-purity geometric isomers and systematically characterized, for the first time, their isomer-specific spectral properties, photoisomerization behavior, UV-shielding capacity, antioxidant activity and skin-related biological activities—highlighting ζ-carotene's promise as a natural ingredient for skin health and photoprotection.