Little's appointment was ratified at a board meeting on Monday morning, with finance director Paul Brasher elected deputy chairman.
He used his first public appearance to heap support on Hird, and reaffirm the club's view the fourth-placed Bombers would be playing in this year's finals.
"James Hird has also got not only my full and complete support but the board's full support and we look forward to James taking us into a successful finals campaign," Little said on Monday.
Hird last week said the club was "very confident" it would be free to play in this year's finals series.
Little said he expected the ASADA report will give the Bombers the chance to defend themselves.
"The ASADA report, we understand, will be made available to the club within the next week or two and we look forward to the opportunity of being able to use this report to answer a lot of the allegations and concerns that have been voiced in relation to the Essendon Football Club," Little said.
Little was deputy chairman to David Evans before Evans announced his resignation on Saturday. He recognised Evans' contribution when accepting the role.
"I'm very honoured and privileged to be elected as chairman of the Essendon Football Club," Little said in a club statement.
"I'd like to pay tribute to the leadership and character of David Evans, who has played a significant role in guiding the club through a very difficult time.
"David Evans leaves an enormous legacy on the Essendon Football Club and I know at the appropriate time he will be recognised and acknowledged by the club for his incredible passion, loyalty and service."
"David is not lost to the Essendon family and I know he will be back at the club very soon."
Little joined the board in 2011 and took on the role of chairman of the fundraising working group for the club's new elite training and administration facility at Melbourne Airport.
In his resignation statement on Saturday evening, Evans pointed to Little as among the people to lead the club out of its crisis.
"What is happening at our club right now is a tragedy, but I know that it will survive," Evans said.
"I believe in the Essendon Football Club and its people and it will get through this crisis with people like Paul Little, James Hird and Ray Gunston as its leaders."
Little was managing director of Toll Holdings from 1986 to 2011 and is still a director of the company.
