The former Los Angeles Lakers star briefly spoke to reporters after landing in Beijing.
He said he believes the North Korean leader wants to change things in his country and called Kim a friend.
Rodman also said that he did not make a plea for the release of Kenneth Bae. The American missionary was arrested in November and sentenced to 15 years of hard labor for what North Korea described as hostile acts against the state.
Rodman once asked on his Twitter account for Kim to set Bae free but has since said the missionary's fate was none of his business. Kim has the power to grant special pardons under the North's constitution.
"Guess what? That's not my job to ask about Kenneth Bae," Rodman told reporters. "Ask (President Barack) Obama about that. Ask Hillary Clinton."
The NBA Hall of Fame and five-time championship winner displayed a stack of photos showing him hugging Kim.
"He's my friend for life. I don't care what you guys think about him," Rodman said.
He said Kim had encouraged Rodman when he goes back to the United States to "say some very good, positive, and very good things about this country, that's what we talked about a lot."
North Korea's official news agency, KCNA, said in a brief report that the two had "a cordial talk," and that Kim invited Rodman back again "any time."
The report said they watched a basketball game together, and Kim hosted a dinner for the sports star.
The Associated Press contributed to this report.