He was taken to the Royal Sussex County Hospital following the incident just before 06:00 BST on Saturday. He is reported to be in a stable condition.
Sussex Police said the incident in Preston Street appeared to be linked to the collapse of a section of railing surrounding the balcony.
The one-way street had to be closed to allow for investigations.
A 20-year old man is in hospital with serious injuries after he fell from a first floor balcony in Brighton.