Chubby, with a round face and sporting Kim's trademark side-shaved haircut, the vendor was pictured cooking skewered meat on a rusty barbecue.
Though his identity remains unknown, he works in the northeastern Chinese city of Shenyang, not far from the border with North Korea.
Like Kim, the vendor has a penchant for high-buttoned jackets, and a smoking habit.
But he appears to lead a simpler existence than his powerful doppelganger - who is reported to enjoy a luxury lifestyle - and was seen at the weekend sitting on a small plastic stool, tending to his meaty wares.
Beijing has long been Pyongyang's closest ally, but the North's continued nuclear programme is said to have chilled ties, and Chinese social media users often skewer the young leader with irreverent criticism.
"This has got to be Fatty the Third's brother - quick, bring him back!" wrote one user of Sina Weibo, a social media service similar to Twitter.
China provides the bulk of North Korea's trade and aid, and another user wrote: "Fatty the Third finally has a money-making career."
