The RNLI said if the alarm had not been raised they could have been recovering a dead body from the sea off Redcar.
Video of the rescue showed a lifeboat crew member speeding out towards the Teesside Wind Farm in the North Sea at around 7.30pm on Monday.
The crewman shouts to the drenched casualty, who is too big to fit in the dinghy and is wearing a hoodie and shorts: “Ey up fella, what are you doing out here?”
He then radios to the Coastguard that the man was in a “£10 dinghy” and had no safety equipment.
The man was then brought back safely to shore and was given safety advice.
Dave Cocks, Lifeboat Operations Manager at Redcar RNLI, said: “This is a good example of the types of incident we repeatedly warn people about.
“It was a reasonably pleasant evening but the wind and tide were a recipe for this to happen.
“We believe the man was in his 30s.
“He was dressed in only a hoodie and shorts, and he didn’t even fit in the toy dinghy.
“If the alarm hadn’t been raised there was every likelihood he’d have drifted out of sight of land and we could well have been bringing a dead body back.”