Seawater batteries (SWBs) directly use sodium ions from seawater for energy storage, reducing reliance on critical materials relative to lithium-based systems. In this Perspective, we examine the potential of SWBs as integrated systems for energy storage, seawater desalination, carbon capture and/or resource recovery. SWBs operate by extracting sodium metal from seawater during charge and returning it upon discharge. The open positive electrode architecture allows simultaneous desalination of the seawater. During discharge, the sodium hydroxide generated in SWBs reacts with carbon dioxide and divalent ions to form stable carbonates, enabling passive carbon sequestration. Brine from the desalination step could be electrochemically converted into valuable resources such as chlorine gas, hydrogen gas, sodium hydroxide and sodium metal. These functions have been developed and experimentally demonstrated either independently or in partially integrated configurations, suggesting the potential for their convergence within a single multifunctional platform. Realizing such integration will require overcoming key barriers, particularly sluggish multi-reaction kinetics, interfacial instability and system-level durability limitations through coordinated advances in materials design and cell architecture.