Newly-appointed CDS Lt Gen Chauhan – who had had a three-star rank during retirement – would be superior to the Army General, Admiral of the Navy and Air Chief Marshal of the Air Force.
The appointment comes over nine months after the post fell vacant following the death of Gen Bipin Rawat.
The court of inquiry has ruled out mechanical failure, sabotage or negligence as a cause of the accident.
CDS Rawat, his wife and 11 defence personnel onboard died in the accident.
A timeline of what happened to the IAF helicopter carrying Chief of Defence Staff Bipin Rawat and others that crashed near Coonoor in Tamil Nadu
After a four-decade service in the India Army, General Rawat had been appointed as the Chief of Defence Staff in December 2019.
Gen Rawat, then a lieutenant general, two pilots and a Colonel survived the crash, which happened due to engine failure.
The chopper, with a total of 14 persons on board, took off from the Sulur air base near Coimbatore and was on its way to Coonoor.
An official said, technical snag or weather could have been the factor due to which crash happened.
The author Nitin Gokhale described the elevation as 'a bold move', contrary to claims at the time that the correct procedures had been followed.