Firefighters rescued Dave the fox who had got stranded on a pontoon on Balladier Walk in Poplar.
The young cub had jumped down onto some man-made reed beds along the canal and couldn't get back up the bank.
The RSPCA was in attendance and called the Brigade.
Firefighters used an emergency rescue boat to take the RSPCA inspectors out to reach the stricken fox.
Station Manager Richard Wyatt, who was at the scene, said: "There was a nest down there so we think he was after his lunch.
"He kept jumping to different sections and eventually ended up in the water. He was quite a slippery little character who almost out foxed us but with a bit of team work with the RSPCA we managed to reach him with the nets they had.
"The RSPCA inspectors named him Dave and they were going to warm him up, give him a bit of food and then release him.
"We would always encourage people to call the RSPCA in the first instance if they see an animal stuck or in distress.
“Firefighters love animals too and we are always happy to assist if the RSPCA require our assistance and specialist equipment, as in this case."
The Brigade was called at 1321 and the incident was over for firefighters by 1547. Two fire engines and two fire rescue units from Poplar, Lewisham, Millwall and Euston fire stations attended.