Valentia Coast Guard requested the crew to launch their inshore lifeboat after walkers reported a person in difficulty in rough seas. He was quickly brought to safety, assisted by another swimmer and members of the public.
The swimmer said he had been alone but two pairs of shoes were found on the slipway, leading to fears that a second person may be in the water.
Gardaí, the Old Head Coast Guard shore unit and Irish Coast Guard helicopter Rescue 115 joined the search but no further casualties were found.
Speaking following the callout, Kinsale RNLI lifeboat operations manager John O'Gorman said: "Thankfully this swimmer was helped ashore and made a full recovery but we would urge everyone to pay particular attention to the RNLI's Respect the Water campaign.
"Irish waters are dangerously unpredictable, especially at this time of year. There are over 200 coastal drownings every year. The RNLI aims to halve that number by 2024 and the RNLI’s Respect the Water campaign will play a key role in achieving this.
"We still want you to enjoy the water, but we also want you to respect the water, acknowledge its dangers and never underestimate its power."
The RNLI urges anyone going on or in the water to let someone know where they are and when they will be back, and to carry a form of communication if at all possible.
If you do see someone in trouble, please do not enter the water to assist unless you are a trained lifesaver. Always dial 999 or 112 and ask for the coastguard.