The alarm was raised after the man was suspected to have been overcome with fumes on a survey vessel working near the Codling Buoy. The all-weather lifeboat launched at 2.45am and was alongside the survey vessel at 3.12am.
Conditions in the area at the time were described as moderate sea with wind southwest Force 3.
The casualty was transferred onto the lifeboat by stretcher and as the lifeboat returned to Wicklow, the crew administered first aid and monitored the casualty.
Due to the low tide in the harbour at the time, the casualty was transferred to the inshore lifeboat and landed ashore at 3.50am. He was met on arrival by a waiting ambulance crew who took him to hospital.
Speaking after the call-out, Wicklow RNLI lifeboat operations manager Des Davitt said: "This was a typically professional response by the volunteer crew of Wicklow lifeboat, who launched within seven minutes of being paged."
The all-weather lifeboat crew launched under coxswain Nick Keogh with mechanic Brendan Copeland, Ciaran Doyle, Carol Flahive, Paul Sillery, Graham Fitzgerald and Peter McCann on board. The inshore crew were helm Barry Spencer, Dave O'Leary and Brian Sinnott.