A statement from organisers said Soares took ill while parading Saturday.
Medical team attended to him on the catwalk and Soares was later taken to a hospital, where he was pronounced dead.
The statement did not provide more details about the 26 years old.
Daily Folha de S. Paulo reported that Soares tripped on his shoelace and fell.
According to the paper, people in the crowd initially thought his fall was part of a performance.
A photo in the newspaper showed the model lying face down on the catwalk while paramedics attended to him.