North Korea also unveiled Kim's yacht and his armored train carriage, where he is said to have died. Among the personal belongings featured in the mausoleum are the parka, sunglasses and pointy platform shoes he famously wore in the last decades of his life. A MacBook Pro lay open on his desk.
North Koreans paid homage to Kim and basked in the success of last week's launch of a long-range rocket that sent a satellite named after him to space.
The launch, condemned in many other capitals as a violation of bans against developing its missile technology, was portrayed not only as a gift to Kim Jong Il but also as proof that his young son, Kim Jong Un, has the strength and vision to lead the country.
The elder Kim died last Dec. 17 from a heart attack while traveling on his train. His death was followed by scenes of North Koreans dramatically wailing in the streets of Pyongyang, and of the 20-something son leading ranks of uniformed and gray-haired officials through funeral and mourning rites.
The mood in the capital was decidedly more upbeat a year later, with some of the euphoria carrying over from last Wednesday's launch. The satellite bears one of Kim Jong Il's nicknames, Kwangmyongsong, or "Lode Star," a moniker given to him at birth according to the official lore.
Cameras were not allowed inside the mausoleum, and state media did not release any images of Kim Jong Il's body.
With the death anniversary came a hint that Kim Jong Un himself might soon be a father.
His wife, Ri Sol Ju, was seen on state TV with what appeared to be a baby bump as she walked slowly next to her husband at the mausoleum, where they bowed to statues of Kim's father and grandfather.
There is no official word from Pyongyang about a pregnancy. In addition, Ri is shown wearing a billowing traditional Korean dress in black that makes it difficult to know for sure.
North Koreans are reluctant to discuss details of the Kim family that have not been released by the state. Still there are rumors even in Pyongyang about whether the country's first couple is expecting.
To honor Kim's father, North Koreans stopped in their tracks at midday and bowed their heads as the national flag fluttered at half-staff along streets and from buildings.
Pyongyang construction workers took off their yellow hard hats and bowed at the waist as sirens wailed across the city for three minutes.
Tens of thousands of North Koreans gathered in the frigid plaza outside, newly transformed into a public park with lawns and pergolas. Geese flew past snow-tinged firs and swans dallied in the partly frozen moat that rings the vast complex in Pyongyang's outskirts.
"Just when we were thinking how best to uphold our general, he passed away," Kim Jong Ran said at the plaza. "But we upheld leader Kim Jong Un. ... We regained our strength and we are filled with determination to work harder for our country."
Speaking outside the mausoleum, renamed the Kumsusan Palace of the Sun, the military's top political officer, Choe Ryong Hae, said North Korea should be proud of the satellite, calling it "a political event with great significance in the history of Korea and humanity."
Much of the rest of the world, however, was swift in condemning the launch, which was seen by the United States and other nations as a thinly disguised cover for testing missile technology that could someday be used for a nuclear warhead.
The test, which the U.N. Security Council said violated a ban on launches using ballistic missile technology, underlined Kim Jong Un's determination to continue carrying out his father's hardline policies even if they draw international condemnation.
Washington said Monday it has no option but to seek to isolate Pyongyang further.
"What's left to us is to continue to increase pressure on the North Korean regime and we are looking at how to best to do that, both bilaterally and with our partners going forward until they (North Korea) get the message. We are going to further isolate this regime," U.S. State Department spokeswoman Victoria Nuland said.
Some outside experts worry that Pyongyang's next move will be to press ahead with a nuclear test in the coming weeks, a step toward building a warhead small enough to be carried by a long-range missile.
Despite inviting further isolation for his impoverished nation and the threat of stiffer sanctions, Kim Jong Un won national prestige and clout by going ahead with the rocket launch.
At a memorial service on Sunday, North Korea's top leadership not only eulogized Kim Jong Il, but also praised his son. Kim Yong Nam, president of the Presidium of North Korea's parliament, called the launch a "shining victory" and an emblem of the promise that lies ahead with Kim Jong Un in power.
The rocket's success also fits neatly into the narrative of Kim Jong Il's death. Even before he died, the father had laid the groundwork for his son to inherit a government focused on science, technology and improving the economy. And his pursuit of nuclear weapons and the policy of putting the military ahead of all other national concerns have also carried into Kim Jong Un's reign.
In a sign of the rocket launch's importance, Kim Jong Un invited the scientists in charge of it to attend the mourning rites in Pyongyang, according to state media.
The reopening of the mausoleum on the anniversary of the leader's death follows tradition. Kumsusan, the palace where his father, Kim Il Sung, served as president, was reopened as a mausoleum on the anniversary of his death in 1994.