The duo who had been taking part in the Devizes to Westminster 125-mile race course were found in distress on the foreshore in front of the Harrods Depository in Barnes , on the morning of the Oxford and Cambridge Universities Boat Race.
They were taken on board the RNLI lifeboat to Chiswick Pier where paramedics from the London Ambulance Service took them into care.
The incident happened just after 9am on Sunday (March 27).
Chiswick RNLI helmsman Luke Dillon said: “One of the pair was suffering from exhaustion and hypothermia, having paddled through the night in wet and windy conditions.
“We were able to assist them, start to warm them up and prevent their condition from deteriorating further.”
More than 300 boats and around 550 paddlers took part in the gruelling race which started on Good Friday and takes place over four days.
Lightning strikes at Boat Race
On Easter Sunday, less than one hour before the 2016 Boat Race poor weather conditions saw lighting strike a tree which caught fire near the podium presentation area in Chiswick.
However there were no reports of injuries and thousands of spectators went on to see Cambridge men take the title from their Oxford competitors in the late afternoon.
RNLI had two E Class lifeboats on duty with four smaller craft manned by lifeguards keeping watch to prevent spectators from getting into difficulties.