Maickel Melamed, 38, of Caracas, Venezuela, made it across the finish line of the 26.2-mile race at 1:30 a.m. Monday. About 100 people cheered him on as he finished. He received a finisher's medal.
He put forth a positive message of achieving dreams and teamwork, offering several inspirational quotes after he completed the race.
"When you give it all you feel peace inside," Melamed said, adding that's his desire for everyone. He also offered a message: "If you dream it, make it happen."
Later, he said, "When you cross this finish line, you think to yourself, 'I can do anything in my life.'"
One of his supporters, Leda Santo Domingo, said he is a survivor and champion.
"We're following him, because we believe that this is almost an impossible thing to do," she said. "He's doing it because his mind is so strong, and he has in the heart a dream."
Melamed started running marathons two years ago and Chicago was his third. He has competed in marathons in Berlin and New York City and plans to tackle the upcoming Tokyo and Boston races.
His time for the Chicago Marathon was 16 hours and 46 minutes.
The winner was Kenyan Dennis Kimetto, who finished the course in 2 hours, 3 minutes, 45 seconds.