The two-and-a-half-foot snake was spotted at 11.30am by the entrance to Parliament Hill Lido in north London.
Rangers took 30 minutes to carefully place the snake into a net and remove it from the park in a carrier box.
Michael Drakonakis, 25, was on his way to the Heath when he saw the episode unfold.
“It’s not every day you see a python on your way to the Heath,” he told Ham and High.
“It’s the biggest one I have ever seen. The enthusiasm and bravery of the animal handlers would have made even Steve Irwin proud.”
Adam King, 25, who was also by the ponds, said: “I did a double take, at first I thought they might be releasing a hedgehog back into the wild.
“Then I realised it was a snake, probably the biggest I’ve ever seen outside of captivity. Huge credit to the animal handlers for dealing with the slippery character so calmly.”
A member of the public notified the City of London Corporation to the snake but it is not known where the reptile came from.
Authorities have been working alongside animal welfare authorities to rehome the python.
Rangers suspect the snake could be a reticulated python.
The species is the longest snake in the world. The reptile is native to South and Southeast Asia.
The population saw a marked increase in sightings around the bird sanctuary pond following the launch of a monitoring programme in 2009.
A spokesperson for the City of London Corporation said: “On Sunday a python was found at the Lido by a member of the public who alerted the Heath team.
“Heath Rangers rescued the snake and are liaising with the relevant animal welfare bodies.”