In December of 1941, Rear Admiral Ben Moreell, then Chief of the Bureau of Yards and Docks, was given the go ahead to create Naval Construction Battalions. The first units were placed under the Navy's Civil Engineer Corps and were comprised of men from civilian construction trades. The Navy wisely focused on skill and training rather than physical requirements. In the beginning the average age of a SeaBee was 37. At the height of World War II, the SeaBees numbered more than 325,000. All told, SeaBees were called in to build and fight on more than 300 islands and 6 continents. SeaBees usually landed very shortly after Marines did in the Pacific and often fought alongside them while building roads, airstrips, bridges, and all sorts of buildings.

After World War II, the SeaBee force was reduced to about 3,500 men. When the Korean War started, some 10,000 more were called into service. When the 1st Marine Division landed at Inchon, the SeaBees landed right alongside them under instense enemy fire. While the Marines battled the enemy forces, the SeaBees built causeways which sped the landing of more men and vehicles. After Inchon, and other landings, the Navy saw how useful the SeaBees could be and did not reduce the force after the cease fire was signed. When the rest of the military demobilized, the SeaBees switched gears.

Starting in 1953 after a major earthquake in Greece, the SeaBees became the "Navy's Goodwill Ambassadors" by visiting remote and under-developed countries. They provided much-needed construction training and assisted in the building of roads, public utilities, and orphanages. They were commonly referred to as "Civil Action Teams."

These "Civic Action teams" continued into the Vietnam War where Seabees, often fending off enemy forces alongside their Marine and Army counterparts, also built schools and infrastructure and provided health care service. After Vietnam, the Seabees built and repaired Navy bases in Puerto Rico, Japan, Guam, Greece, Sicily, and Spain. Their civic action projects focused on the Trust Territories of the Pacific.

In 1971, the Seabees began their largest peacetime construction on Diego Garcia, a small atoll in the Indian Ocean. This project took 11 years and cost $200 million. The complex accomodates the Navy's largest ships and the biggest military cargo jets. This base proved invaluable when Iraq invaded Kuwait in August 1990 and Operations Desert Shield and Desert Storm were launched. During the Gulf War, more than 5,000 Seabees (4,000 active and 1,000 reservists) served in the Middlle East. In Saudi Arabia, Seabees built 10 camps for more than 42,000 personnel; 14 galleys capable of feeding 75,000 people; and 6 million square feet of aircraft parking apron.