There was heavy exchange of fire between a group of five poachers and forest guards near Sundari Camp of the Park's Burapahar range around 6 AM, KNP sources said.
The guards then recovered the carcass of the bullet-riddled rhino with its horn intact, they said.
The poachers, however, fled away after the encounter.
This is the fourth rhino to have fallen victim to bullets of poachers this week.
On January 29, a rhino was killed and its horn sawed off near the Hatibandi Camp under Bagori range of the Park along Nagaon and Karbi Anglong districts.
The same day another rhino was killed and its horn removed by poachers near Borholla camp in the Burapahar range of the Park.
In the third incident on January 30 poachers killed a rhino when it was being escorted back by forest guards to KNP after it had strayed to Majuli the night before.