Her first duty assignment was in the autumn of 1945 in a three-month tour as part of the overall occupation forces following the surrender of Japan.

Following the outbreak of war in Korea in June 1950, McKean sailed from Long Beach, California, joining the 7th Fleet in August.

On the night of 25 November 1950, hundreds of thousands of Chinese troops had crossed the Yalu River into North Korea to attack advancing U.N. forces.

The relief of UN troops depended upon air cover and firepower from planes of carriers stationed off the eastern coast.

Under a protective canopy of naval air cover, the leathernecks broke through 10 December at Chinhung-ni and moved to Hŭngnam for evacuation.

The United States Navy completed the Hŭngnam withdrawal of 24 December after embarking 105,000 troops, 91,000 refugees, and vast quantities of military cargo.

At that time TF 77 was the largest assembled fleet since World War II, with four carriers, the battleship Missouri, two cruisers and over 30 destroyers.

According to the book Blind Man's Bluff: The Untold Story of American Submarine Espionage by Sherry Sontag and Christopher Drew; "U.S. intelligence officials have long believed that a U.S. surface ship sank a Soviet sub that came close to an aircraft carrier attack force in 1950, early in the Korean War, according to two former intelligence officers."

About an hour after clearing the sub nets, but with the Japanese shoreline still in sight, she received a hard contact from sonar.

The aircraft then reported sighting air bubbles near the location of the first attack and an oil slick, which grew larger as time passed.

The morning of 19 December, one of the three anti-sub airplanes overhead reported a torpedo wake passing astern of the McKean.

After January 1951, McKean joined Task Force 95 for shore bombardment duty & blockade work around Wonsan, Songjin and Chinjŏn.

The task group consisting of one cruiser and four destroyers were the first U.S. ships to visit Melbourne since the end of World War II.

Regarding this tour off the Vietnam coast, Commanding officer J. E. Mitchell wrote in a 29 December 1965 letter to the state-side families of the McKean sailors: "...If you are interested in vital statistics, here are some.

Figured through our arrival at Long Beach on 13 January, McKean will have steamed a total of 57,014 miles – more than twice the distance around the world at the Equator.

Our average steaming speed was about 17 knots, or approximately 20 miles per hour, during which the ship consumed 3,748,420 gallons of fuel oil.

Over 1,000 rounds of five inch projectiles were fired, weighing approximately 25 tons..."[2] After this tour, she returned to Long Beach and attended two fleet exercises, "Eager Angler" and Baseline II."

In November 1966, the McKean returned to the Western Pacific for Search and Rescue operations at the Gulf of Tonkin off the north coast of Vietnam.

From Sasebo, as part of Operation Formation Star, the McKean was sent to the coast of Korea to join United States naval pressure on the North Korean government to win the release the crew of the Pueblo (AGER-2), which had been seized 23 January 1968.

In June 1970 she went back to Long Beach to take on more crew and to continue training and to take part in numerous U.S. Navy exercises.

In December 1971, the McKean was sent to the Bay of Bengal as part of Task Force 74 to safeguard United States interests there while the Indo-Pakistani War was waged.

After rejoining the fleet, the McKean saw port calls at Singapore, Hong Kong, New Guinea and again Australia and New Zealand.