The selection committee in Mohali on Thursday named Dravid, 32, captain for a series of seven limited-overs internationals against Sri Lanka and five one-dayers against South Africa at home from October 25 to November 28.
"It is an honour and a privilege to have been named as captain of India for the next two series," Dravid said after playing for the World XI on the opening day of the Super Test against Australia at the Sydney Cricket Ground Friday.
"We will be playing against two great teams, and I am very much looking forward to the challenges that both series will present."
Dravid said he was informed of his appointment by Indian cricket board secretary Karunakaran Nair and the chairman of selectors Kiran More during the tea interval at the SCG.
"As it was during a game it was quite a brief conversation in which they congratulated me on my appointment. The chairman of selectors mentioned that there had been some encouraging signs during the recently concluded Challenger Trophy.
"I look forward to returning to India and meeting up with the coach, selectors and other players to make plans for the matches that are ahead of us."
Dravid's elevation to the top job was widely predicted in the Indian media as Ganguly struggled with injury, poor batting form and a damaging spat with coach Greg Chappell.
Ganguly, whose 21 Test and 76 one-day wins as captain are an Indian record, missed the recent domestic one-day trial matches here due to a tennis elbow injury.
With India also due to play Test series against Sri Lanka, Pakistan, England and the West Indies in a gruelling schedule till July, the selectors clearly did not want to take chances with an uncertain Ganguly at the helm.
Dravid, a prolific top-order batsman and longtime deputy to Ganguly, led India in five Tests and 17 one-dayers in the captain's absence, with mixed results.
Under Dravid, India won and lost two Tests each against Australia and Pakistan last season, while the fifth against New Zealand was drawn.
In 17 one-dayers as captain, Dravid won seven matches and lost nine, while one was rained off.