Decatur was commissioned on 19 June 1998 in Bath, Maine, with the official ceremony taking place 29 August 1998, at the Tom McCall Waterfront Park in Portland, Oregon.

In April 1999, the warship conducted a short cruise to the Northwest, visiting Decatur Island, Washington, and Vancouver, Canada, before returning to San Diego in early May.

After a second visit to Washington in August, Decatur sent a boarding team of Damage Control Experts to assist MV Gardenia Ace—a car carrier—which had suffered a fire in her engine room.

[citation needed] Upon completion of her final missile tests and sea trials, Decatur commenced her first western Pacific deployment on 7 January 2000.

Following the terrorist plane hijackings and crashes in New York, Washington and Pennsylvania on 11 September, the destroyer put to sea for Operation Noble Eagle off the coast of the San Francisco Bay Area.

Returning to San Diego on 23 September, the warship spent seven weeks preparing for her deployment with the John C. Stennis battle group on 12 November.

In April 2013, Decatur was sent to the Western Pacific near the Korean Peninsula, to join two other destroyers, John S. McCain and Fitzgerald, in response to growing threats and an increase in belligerent statements and actions by North Korea's leadership.

[8][9][10] On 30 September 2018, Decatur and the Chinese destroyer Lanzhou were involved in a near-collision when the two ships came within 45 yards (41 m) of one another in the South China Sea.

Crossing in the center of the crown is an English officer’s sword and a seax.The traditional Navy colors were chosen for the shield because dark blue and gold represents the sea and excellence respectively.

The seax signifies a series of victories by Stephen Decatur over sea forces of North African terrorist nations.

The English officer's sword symbolizes Decatur's victory over HMS Macedonian during the war of 1812 in one of the greatest single ship actions of naval history.