The outing comes as China has sought to strengthen its role as a mediator between the US and North Korea, where Beijing claims compelling security and economic interests.
The North's leader, who is believed to have landed in the Chinese capital Tuesday morning, was expected to head to the Great Hall of the People to meet with Chinese President Xi Jinping, though no official agenda was released.
Dozens of security vans, police cars and armoured vehicles lined streets around Beijing's Diaoyutai State Guesthouse - where Kim had stayed in his previous visit.
When it comes to North Korea, no one puts Beijing in a corner
A motorcade accompanying a black limousine was seen leaving the compound late Tuesday afternoon as police cleared the way. A plainclothes officer grabbed an AFP video journalist and demanded that the footage be deleted.
The visit comes as the United States, which relies on China to enforce sanctions against Pyongyang, stands on the brink of a potential trade war with Beijing, adding an extra layer of uncertainty and a possible pressure point to be exploited by North Korea's powerful ally.
Chinese state broadcaster CCTV reported that Kim would be in Beijing through Wednesday.
"We hope this visit will help deepen the China-DPRK relations and strengthen our strategic communication on major issues to promote regional peace and stability," foreign ministry spokesman Geng Shuang told a regular press briefing.
The visit is the North Korean autocrat's third to China since March, when he made his inaugural foreign trip as leader.
North Korea's Kim visit Beijing; South Korea, US halt military drill
Previous trips had been kept secret until Kim returned home. It was not clear why Chinese state media broke with the precedent.
In addition to discussing last week's summit, Kim is expected to ask China for help in easing economic sanctions, in return for his pledge to denuclearise, according to Wang Dong, an international relations expert at Peking University.
"The Chinese and North Korean leaders are carrying out consultations on how to jointly move the Korean nuclear issue forward."
Following the historic US-North Korea summit in Singapore a week ago, China suggested the UN Security Council could consider easing the economic restrictions on its Cold War-era ally.
China may not have been at the table for the historic summit in Singapore but it retains strong influence behind the scenes, Dong said.
The visit shows that China is "key" to the talks, Wang said.
"It reflects that China is indispensible to the entire Korean nuclear issue."
In a joint statement following the Singapore summit, Kim pledged to "work toward the complete denuclearisation of the Korean Peninsula".
Trump hailed this as a concession but critics said the stock phrase long used by Pyongyang stopped short of longstanding US demands for North Korea to give up its atomic arsenal in a "verifiable" and "irreversible" way.
It is now urgent for Xi and Kim to discuss how North Korea will work towards meeting US demands, said Beijing-based international relations commentator Hua Po.
"There may be differences ahead between the DPRK and the US in regards to denuclearisation, because the US wants irreversible and verifiable denuclearisation. It may be difficult for Kim Jong Un to accept," Hua told AFP.
"Therefore, both China and the DPRK want to strengthen communication and form an overall strategy to deal with the United States going forward," Hua added.
In return for the denuclearisation pledge, Trump made the shock announcement that he would stop joint military drills with South Korea, long seen as a provocation by Pyongyang and Beijing.
Analysts saw this as a clear sign of Beijing's influence.
Beijing has repeatedly called for a "suspension for suspension" approach where the North would stop its nuclear and missile activities in exchange for the US and South Korea halting military exercises.
But Washington had previously rebuffed the proposal.
On Tuesday, the US and South Korean militaries confirmed they have called off scheduled joint exercises following Trump's order.
Trump had raised eyebrows by describing the exercises as "provocative" - a term used by the North.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ