The male rhino, which strayed from the flooded park, was shot at inside the Jagadamba Tea Estate bordering Bagori range and its horn removed on Thursday leaving it bleeding at the spot, officials said.
The rhino struggled for its life but succumbed to injuries though a veterinary team rushed to the spot to treat the injured pachyderm.
During the last three days, five rhinos have been killed while during the current year. Seventeen rhinos have been so far killed and their horns removed by poachers.
Assam Chief Minister Tarun Gogoi said his government has already recommended a CBI inquiry into rhino killings and was confident that it would help in nabbing the poachers.
He claimed poaching has come down considerably since the days of the earlier Asom Gana Parishad government in the state.
"The state forest department was capable of dealing with the situation and the army would be deployed along the Karbi Hills only to help them," Gogoi told reporters while reviewing the flood situation of Morigaon district.
Assam Forest Minister Rockybul Hussain reviewed the prevailing situation in Kaziranga and held a meeting with forest officials to prevent further incidents of poaching.
Meanwhile, conservation group Aaranyak alleged that failure of intelligence network, lack of coordination between the forest department and Karbi Anglong Autonomous District Council Forest department and commitment on the part of officials concerned were responsible for the prevailing situation.