Chinese Gen. Fang Fenghui made the promise, the first of its kind, in a meeting with Gen. Jung Seung-jo, the chairman of South Korea's Joint Chiefs of Staff, The Chosun Ilbo reported Friday.
Some 500 South Korean POWs are believed to still be alive in the north since the Korean War ended in 1953.
A report by the Joint Chiefs of Staff after last week's meeting in Beijing said China offered "active support" in repatriating any POWs and their families now in North Korea who are able to escape to China.
A South Korean official, who was not identified, said the pledge "marks a major step forward given Beijing's position on the matter in the past."
The official characterized the statement as "a symbol of the developing relationship between South Korea and China."
South Korean President Park Geun-hye recently visited China. The report said Fang told Jung Beijing viewed her visit as a major step forward in improving relations between the nations.