The encounter was captured on camera by research scientist and photographer Mark Ziembicki, 46, during a recent visit to the east coast of South Africa.
In one photo, the Nile croc can be seen closing in on the 100lb bull shark pup - its mouth wide open, ready to gobble up its prey.
Another image shows that the crocodile had managed to get the shark upside down between its jaws, unable to escape.
According to Ziembicki, who from North Queensland, there were two reasons why the freshwater species had been washed downriver and into saline coastal waters.
He credited the recent opening of St Lucia estuary and excessive rainfall inland, saying these factors led to the unlikely meeting of the two apex predators.
Ziembicki was able to capture the attack, which happened just 60 feet away from where he was standing, using a Canon 5D SLR camera with a 300mm lens.
He explained that he'd been watching the two animals in the area for several hours, and had been curious to see what would happen if they stumbled across each other.
He recalled: "While we were busy taking photos of another crocodile on the bank there was some commotion about one-hundred feet away.
"A local resident of the area who was also there, shouted there was a croc eating a shark.
"We turned to see the shark thrashing away in the crocodile's mouth.
"It spent about ten minutes with the shark in its jaws, tossing it about.
"The shark gradually moved less until it was eventually swallowed whole headfirst.
"We were completely taken by surprise.
"We'd been observing both the crocodiles and sharks in the area for several hours and were wondering what would happen if the two might meet.
"We had our answer I guess, although obviously there was a size mis-match on this occasion."
Crocodiles have the most powerful bite in the animal kingdom, with the Nile species' grip exerting a force eight times greater than that of a Great White Shark.
According to National Geographic, Nile crocodiles can weigh up to 1,650lbs, but usually average around 500lbs - meaning Ziembicki's croc was a particularly large beast.
"The diet of the Nile crocodile is mainly fish, but it will attack almost anything unfortunate enough to cross its path, including zebras, small hippos, porcupines, birds, and other crocodiles," the website says.
"It will also scavenge carrion, and can eat up to half its body weight at a feeding."