In the annual procession -- which sometimes provides a peek at the country's latest missile program -- military bands led thousands of soldiers across Kim Il-sung Square in the center of the capital, South Korea's Yonhap News Agency reported.
North Korean leader Kim Jong-un and visiting Chinese Vice President Li Yuanchao reviewed the parade.
The three-year Korean War ended in 1953 with the signing of an armistice agreement between the North and the South, but the two countries are still technically at war.
South Korean President Park Geun-hye pledged in Seoul that provocations by the North will not be tolerated, but said Seoul will work on building trust with Pyongyang, the BBC reported.
"I urge North Korea to give up the development of nuclear weapons if the country is to start on a path toward true change and progress," she said.
U.S. President Barack Obama observed the anniversary with a brief appearance at the Korean War monument in Washington.
Korea is regarded by many as a "tie" -- because neither side was able to claim victory -- but Obama reassured veterans in attendance their efforts were not in vain, USA Today reported.
"That war was no tie -- Korea was a victory."
Obama pointed to the 50 million South Koreans who live in a free society today, "in stark contrast to the repression and poverty of the north, that is a victory, and that is your legacy."