The man became stranded on an island because the reptile stalked him when he tried to leave by kayak, rescuer Don Macleod told broadcaster ABC.
Mr Macleod said he rescued the man on Saturday after spotting a light on Governor Island, near Kalumburu.
The crocodile was around six m (20 ft) long, Mr Macleod said.
The unidentified New Zealander had planned to kayak back to the mainland. But he "came to the conclusion very quickly that he couldn't get off [Governor Island] without attracting [the] crocodile", Mr Macleod said.
"[It] started following him around so he made it back to the island," he added.
Mr Macleod said he had seen the crocodile "several times" before.
"He was going by quite fast one day and he just happened to surface alongside me as I was going past... My boat is 20 ft long and he was well up on the 20 ft mark."
The tourist said he did not know there were crocodiles in the area, Mr Macleod said. "A lot of people are a bit naive about these things."
"Even though the crocodiles have been reduced along the coast by this poaching business, there's still a number of these very old ones that are cunning and certainly on the lookout for an easy meal. He's very, very lucky," Mr Macleod told ABC.
"He wouldn't have made it much longer without water because he seemed to be a bit distressed when we found him."
Last week, a man was killed by a crocodile as he swam in a river in Australia's Northern Territory during a birthday party.
