The incident had been reported to the London coastguard who sent in the RNLI crew from Chiswick to the incident at 5.24pm on Sunday (July 10).
The river is known for its strong currents and cold temperatures and the incident caused concern to rescue crew members.
Rob Archibald, Chiswick RNLI lifeboat helmsman, said: “Thankfully, when we arrived on scene these two chaps were near the bank of the river underneath the bridge, and they both safely got out.
“But it could easily have been another story – we have had people jump off bridges and never be seen again; or at least, not alive.
"I would urge the public, please be aware of the risks, and please – respect the water.”
The RNLI has launched its Respect the Water campaign to halve the number of accidental drownings by 2024.
The campaign is targeted at adult men, who account for a majority of the incidents, which between 2011 and 2014 saw men have accounted for three-quarters (75%) of deaths.
Chiswick lifeboat crew are warning people of the deadly river currents which can move as fast as six knots and the added risk of cold water shock which can be a potential recipe for disaster