Kim left on Sunday in a trip that will include meetings with President Vladimir Putin, state news agency KCNA said.
American officials, who first reported that the visit was imminent, say the discussions are likely to include a possible deal for North Korea to provide Russia with weapons for the war in Ukraine.
Kim was accompanied by top government officials including military personnel, KCNA said.
Among the delegation are prominent military members of the ruling party, including Munitions Industry Department Director Jo Chun Ryong, and one analyst said the make-up of the delegation suggests the visit will mainly focus on defense industry cooperation and security affairs.
"The presence of Jo Chun Ryong indicates that North Korea and Russia will conclude some type of agreement for munitions purchases," said Michael Madden, a North Korea leadership expert at the Washington-based Stimson Center.
Kim was accompanied by top government officials including military personnel, KCNA said.
Among the delegation are prominent military members of the ruling party, including Munitions Industry Department Director Jo Chun Ryong, and one analyst said the make-up of the delegation suggests the visit will mainly focus on defense industry cooperation and security affairs.
"The presence of Jo Chun Ryong indicates that North Korea and Russia will conclude some type of agreement for munitions purchases," said Michael Madden, a North Korea leadership expert at the Washington-based Stimson Center.
"We will continue to strengthen our friendship," he said.
Both Moscow and Pyongyang have denied earlier U.S. accusations that they had conducted arms deals, but the two countries have vowed to boost defense ties.