The inshore lifeboat from Falmouth was called to a wedding party on board a pleasure boat on Saturday after a passenger suffered a suspected heart attack.
The RNLI was sent to the Truro River near Malpas just after 5.30pm after the boat Moyana sent a VHF call reporting a medical emergency, and ambulance paramedics were also tasked to meet the boat at the landing stage at Malpas.
Upon the lifeboat's arrival, the Moyana was already alongside the pontoon berth and a paramedic was on board making an initial assessment.
An RNLI spokesperson said: "Two lifeboat crew volunteers trained in casualty care were placed on board the Moyana to assist with the treatment of the casualty. The inshore lifeboat's stretcher was then used to transport the casualty ashore to an ambulance which had by then arrived on scene.
"The skipper and crew of the Moyana are to be commended for the professional way in which they handled the incident ensuring that the casualty was able to receive medical treatment as quickly as possible."