Xi became the first Chinese head of state to visit Pyongyang in 14 years and the fifth since the two nations established diplomatic relations in 1949.
The Chinese President and his wife, Peng Liyuan, arrived at Pyongyang's Sunan International Airport earlier in the day and were greeted by the North's leader and his wife, Ri Sol-ju, the People's Daily reported.
Close to 10,000 North Koreans waved flowers and chanted welcoming slogans at the airport, it said.
Xi and Kim reviewed an honour guard, with the Chinese leader being greeted with a 21-gun salute. The North's military band performed the national anthems of the two countries.
Hundreds of thousands of people lined the streets of Pyongyang, waving flowers and the flags of both the countries and chanting slogans, such as "DPRK-China friendship", as a motorcade carrying the two leaders in a roofless vehicle headed to central Pyongyang.
The leaders later held summit talks.
"The China-North Korea friendship is a strategic choice made by the two sides with a long-term and overall perspective and will not waver due to changes in the international situation," Xi said during his meeting with Kim, adding that the friendship accords with the aspirations of both peoples, the fundamental interests of both countries and the development trend of the times.
Noting that Beijing-Pyongyang ties have now entered a new historical period, Xi said that the Communist Party of China (CPC) and the Chinese government "attach great importance to the friendly and cooperative relations between the two countries".
The Chinese leader said that it was "a steadfast policy of the CPC and the Chinese government to maintain, consolidate and develop China-North Korea relations".
For his part, Kim expressed a "hearty" welcome to Xi on behalf of his Workers' Party of Korea (WPK), government and people of North Korea, noting that more than 250,000 people flocked to the streets in Pyongyang to welcome the Chinese leader.
The visit, which came upon the 70th anniversary of bilateral diplomatic ties, "represented a huge encouragement and political support for the party, government and people of North Korea and bore great significance in the history of Democratic People's Republic of Korea (DPRK)-China relations", he added.
Kim said that he fully agreed with "the insightful analysis and future plan Xi made on bilateral relations and that it was an unswerving policy of the DPRK's party and government to carry forward the DPRK-China friendship from generation to generation".
( With inputs from IANS )