Kim, dressed in his usual black, high-collared suit and flanked by top military officials, cut a red ribbon and laid a wreath at the cemetery's main monument, a giant stone rifle barrel with a fixed bayonet pointing to the sky.
The ceremony, one in a series of national events that will culminate in a huge military parade in Pyongyang on Saturday, was conducted in front of the cameras of the international media, who have been invited to the North Korean capital for the anniversary celebrations.
Security was extremely tight at the cemetery event.
Women wearing the traditional Korean hanbok dress fanned themselves as they lined up patiently in the humid summer heat to be screened airport-style by soldiers with security wands before being allowed into the venue.
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The men either wore dark suits and ties or, in the case of the veterans, military uniforms some covered from neck to waist in medals.
After Kim Jong-Un had completed his inspection, the invited guests descended on the terraced ranks of gravestones looking for their relatives.
"This was my eldest brother" one elderly veteran Kim Byong-Ryong told AFP as he pointed to one of the stones.
"He joined up when he was just 18 and was killed in the last year of the war. Three of my other brothers were killed as well."
"It's a great honour," said Hwang Sung-Nam, 67, who had brought his wife to see the grave of his father who died in 1985 and was given a grave in the cemetery because of his exceptional war record.
"This will help keep his memory alive forever," Hwang said.