The indigenous woman was attacked in a remote area 206 kilometers (128 miles) southwest of the community of Yirrkala, NT WorkSafe said.
The woman was taken by the crocodile at Gan Gan, East Arnhem.
Police are on their way to a remote part of Arnhem Land after reports a female Aboriginal ranger was taken by a crocodile.
"The family noticed she was missing and the bucket she was carrying was found nearby", he said.
The woman's body and the crocodile were found just before 5pm, less than one kilometre from the scene.
"They heard some splashing". Local wildlife rangers killed the crocodile. "She was up to waist deep in water".
The incident occurred at about 10am Friday and is being investigated by NT WorkSafe.
The woman was an employee of the Laynhapuy Homelands Aboriginal Corporation, which supports indigenous communities across the East Arnhem region and runs the Yirralka Rangers program.
Saltwater crocodile numbers have exploded since they were declared a protected species in 1971, with recent attacks reigniting debate about controlling them.
According to the study, 14 people were killed by crocs from 2005 to 2014, compared to 10 deaths in the 33 years to 2004.