Solar energy is an inexhaustible renewable energy source. Among the various methods for solar energy conversion, photocatalytic hydrogen (H₂) production is considered as one of the most promising ways. Since Fujishima pioneered this field in 1972, photocatalytic water splitting to produce H₂ has received widespread attention. Up to now, abundant semiconductor materials have been explored as photocatalysts for pure water splitting to produce H₂. However, photocatalytic seawater splitting is more in line with the concept of sustainable development, which can greatly alleviate the problem of limited freshwater resource. At present, only few studies have focused on the process of H₂ production by photocatalytic seawater splitting due to the complex composition of seawater and lack of suitable photocatalysts. In this review, we outline the most recent advances in photocatalytic seawater splitting. In particular, we introduce the H₂ production photocatalysts, underlying mechanism of ions in seawater on photocatalytic seawater splitting, current challenges and future potential advances for this exciting field.