As North Koreans continued to grieve, pictures of Kim's body lying in a glass coffin surrounded by flowers were broadcast on state television.
GlobalPost analysis: Kim Jong Il dead: What's next for North Korea?
Kim, who is lying in state at Pyongyang's Kumsusan Memorial Palace, was dressed in his trademark khaki tunic, with a red sheet covering most of his body.
State television reported:
"Comrade Kim Jong Un ... paid a visit to the body of comrade Kim Jong Il with party, government and military officials and expressed condolences with the deepest sorrow."
Elsewhere in the palace, the body of Kim's father, Kim Il Sung, North Korea's founding president, is also on display, AFP reported.
A period of national mourning has been declared until December 29th – a day after Kim's funeral.
North Korea's “Dear Leader”, who had been in power since the death Kim Il Sung in 1994, died of a heart attack on Saturday, while on one of his train trips, state media reported.
Find GlobalPost's full coverage of Kim Jong Il's death here.
South Korea, which has been put on high alert following Kim's death, has sent its condolences to the North Korean people, the BBC reported.
The South is reconsidering a plan to display Christmas lights near the countries' border, which is upsetting for the North.