The development of sustainable cementitious materials is essential and urgent for the construction industry. Benefiting from excellent engineering properties and a reduced greenhouse gas footprint, alkali-activated materials (AAM) are among the robust alternatives to Portland cement for civil infrastructure. Meanwhile, concrete production also accounts for around 20% of all industrial water consumption, and the global freshwater shortage is increasing. This review discusses recent investigations on seawater-mixed AAMs, including the effects of seawater on workability, reaction mechanism, shrinkage, short and long-term strength, binding of chloride and corrosion of steel reinforcement. Attention is also paid to the utilization of sea sand as aggregate, as well as discussions on the challenges and further research perspectives on the field application of AAMs with seawater and sea sand.