The refusal meant that the remains of the other 437 Chinese soldiers were caught in the long and sometimes violent standoff between the two Koreas.

A breakthrough came last June during a visit by President Park Geun-hye of South Korea to China. As part her efforts to cultivate closer ties between the countries, she offered to send the Chinese remains home. China is North Korea’s last remaining major ally, but it has appeared intent on closer ties with South Korea as part of its strategy of countering United States influence in the region.

And under Ms. Park, South Korea — while still a close ally of Washington — has also seemed committed to better relations with China, which has overtaken the United States as South Korea’s biggest trading partner since Beijing normalized its relations with Seoul in 1992. Each year, millions of Chinese tourists visit South Korea.

“The repatriation today will be a landmark for the two countries in healing the trauma from the past and moving toward co-prosperity,” South Korea’s deputy defense minister, Baek Seung-joo, said during a ceremony held at Incheon International Airport, west of Seoul.

During the ceremony, the Chinese ambassador, Qiu Guohong, placed Chinese flags on the dark brown coffins that contained the remains, which were then carried aboard a plane by Chinese soldiers. The remains of the soldiers, the last from China that have been found, are expected to be interred in the resting place for China’s Korean War dead, known as the Resist America and Aid Korea Martyrs Cemetery, in northeastern China.