Poachers had killed the rhino inside the national park under Bagori forest range.
"Forest guards had found the dehorned bullet injuries carcass of a male rhino inside the park on Friday morning, " an official of KNP said.
Flood waters submerged over 70 forest camps in the national park.
The official said that, many wild animals had crossed the NH-37 and entered into the nearest Karbi hills following the worsened flood situation in the national park.
(Reporting by Hemanta Kumar Nath)