According to reports, the incident happened at the 4-star Hotel Brisa Sol, shortly after 5am on Tuesday morning, when the Irishman plummeted from his third-floor balcony.
The 33-year-old man is believed to have been on holiday with his parents and his wife, and was assisted by INEM emergency medics before being rushed to nearby Faro hospital due to the severity of his injuries.
Police were understood to be investigating the incident but initially no foul-play was thought to be involved.
Some media reports quoting local sources claimed the man was unconscious when he was found, and is believed to have ended up sandwiched between a wall and an air conditioning unit.