Freshwater is conventionally used to produce concrete, but freshwater scarcity has become a significant challenge worldwide. The aim of this study is to experimentally investigate the workability and strength of Portland cement concrete mixed and cured with Nembe seawater. The initial and final setting times and slump of fresh concrete mixed with freshwater and seawater were determined. Four sets of concrete specimens were produced for the compressive strength tests: concrete cast and cured with freshwater, cast with freshwater and cured with seawater, cast with seawater and cured with freshwater, and cast and cured with seawater. The use of seawater for mixing concrete decreased the initial setting time of the cement paste and the slump of concrete by approximately 36% and 54%, respectively. Concrete specimens mixed with seawater and cured with freshwater exhibited the highest compressive strengths at the 60 th and 90 th days of curing. Although the concrete mixed with seawater yielded slightly higher compressive strengths than concrete mixed with freshwater, the difference between using freshwater and seawater as mixing and curing water in terms of compressive strength was minimal.