Edward Nino Hernandez, 24, weighs only 10kg (22lbs). His mother said he had not grown since he was two years old.
Mr Hernandez, who works part-time as a dancer, told the Associated Press: "I feel happy because I'm unique."
The previous record holder was He Pingping of China, who was 4cm (1.5 inches) taller and died in March - before Mr Hernandez was discovered.
Mr Hernandez is not expected to keep the title for long, however, as Khagendra Thapa Magar of Nepal is expected to take the title when he turns 18 in October.
Khagendra, currently recognised as the world's shortest living teenager, is only 56cm (22in) tall. The shortest man on record was Gul Mohammed of India, who measured just 57cm - 1cm taller than Khagendra.
Mr Hernandez's mother, Noemi, said doctors in the Colombian capital, Bogota, never explained why he had grown only 40cm since birth.
She said doctors at the National University studied him until he was three and then lost interest. Her youngest child, 11-year-old Miguel Angel, is himself only 93cm (37in) tall
Mr Hernandez left school in the eighth grade and now earns some money dancing at department stores. He is also currently playing the role of a drug dealer in a film.
Although he liked the attention, he said there were some drawbacks.
"It bothers me that people are always touching me and picking me up."
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