Washington and Seoul say Russia has provided Pyongyang with technical support for its satellite programme and sent aid to the food-scarce kingdom.
The visit comes nine months after Putin hosted Kim on a rare foreign trip to the Russian Far East, where the two heaped praise on each other.
Russia and North Korea, which share a short land border, have historical ties as the Soviet Union helped establish the tiny state after the Korean War in the 1950s.
Russia was one of the few countries to have a working relationship with Pyongyang since the collapse of the Soviet Union.
This will be Putin's second visit to China while he is in power; he had earlier met Kim Jong Un's father, Kim Jong Il, soon after becoming president 24 years ago.
At the time, Putin traveled frequently and regularly visited the United States and Europe.
Russia now finds itself under heavy international sanctions and the Kremlin leader has become persona non grata in much of the Western world, and is officially wanted by the International Criminal Court.
Moscow said Putin would travel from North Korea to Vietnam.