The Sea King became operational with the United States Navy in June 1961 as the HSS-2; the aircraft's designation subsequently changed to SH-3A when the unified aircraft designation system was introduced. It was used primarily for anti-submarine warfare, detecting and tracking Soviet submarines and, in time of war, would be used to attack enemy submarines as well.  Night-time ASW operations were possible, with considerable difficulty.  The Sea King was widely exported, particularly for its anti-submarine capabilities, and was operated in large numbers by several nations, including Brazil, Italy, Japan and the United Kingdom.

The SH-3 became the primary helicopter for the retrieval of manned space capsules, starting with the recovery of Mercury-Atlas 7 in May 1962.   In February 1971, a SH-3A, operating from the amphibious assault ship USS New Orleans, performed the recovery mission of Apollo 14. 

During the 1990s, the Sea King was replaced in the ASW and SAR roles by the U.S. Navy with the newer Sikorsky H-60 Sea Hawk.  However, the SH-3 continued to operate in reserve units in roles including logistical support, search and rescue, and transport. On 27 January 2006, the SH-3 was ceremonially retired at NAS Norfolk, Virginia, by Helicopter Combat Support Squadron 2 (HC-2).