Gen Chauhan, a former Eastern Army Commander, took charge as the country's senior-most military commander over nine months after first Chief of Defence Staff (CDS) Gen Bipin Rawat died in a helicopter crash in Tamil Nadu.
Speaking to reporters, Gen Chauhan said the security challenges facing the nation will be dealt with jointly by the three services.
"I am proud to be assuming the responsibility of the highest rank in the Indian Armed Forces. I will try to fulfill the expectations from the three services and tackle all challenges and difficulties together," he said.
He became the first retired three-star Lt General-rank officer to return to the service as a four four-star General.
Gen Chauhan will also be the Principal Military Advisor to the Defence Minister on all tri-service matters as well as head department of military affairs as its secretary.
He will also be the Permanent Chairman of the Chiefs of Staff Committee (COSC), the defence ministry said.
The CDS called on Defence Minister Rajnath Singh shortly after taking charge of the top office.
Before assuming charge of the CDS, Gen Chauhan paid tributes to India's fallen soldiers at the National War Memorial. His father Surendra Singh Chauhan was also present at the memorial.
He was also accorded a tri-services guard of honour at the lawns of the South Block in the Raisina Hills in presence of Army Chief Gen Manoj Pande, Chief of Air Staff Air Chief Marshal VR Chaudhari and Navy Vice Chief Vice Admiral SN Ghormade.
With agency inputs
