Ridley began his tenure as the club reopened for the fall after being closed since late May.
Ridley cited club founders Bobby Jones and Clifford Roberts -- the club's first chairman -- in a statement he released.
"Throughout my life, Bobby Jones has been my idol and role model,'' Ridley said "I remember meeting Clifford Roberts during my first visit to Augusta National as an amateur invitee more than four decades ago. So to become Chairman of Augusta National and the Masters is beyond humbling. I stand ready to embrace the responsibilities that come with this important position, strengthened by the lessons the sport teaches and the example of those who have provided leadership to me over the years.
"As Chairman, I will always look to Jones and Roberts as a source of wisdom and inspiration. I fully subscribe to their mandate of constant improvement and their commitment to maintaining the highest standard in all that we do. I pledge to use my deep-rooted respect for the customs and traditions they established to further elevate our Club and Tournament, while continuing their mission of contributing to the development of the sport around the world.''
A Tampa real estate attorney, Ridley, 65, has been an Augusta National member since 2000. He served as the head of the Masters competition committees in 2007 under previous chairman Billy Payne, who announced his retirement last month and named Ridley as his successor.
Prior to that, Ridley had served for years in volunteer positions with the United States Golf Association, including as its president in 2004-05.
Ridley becomes the first Masters chairman to have played in the tournament, doing so in 1976, 1977 and 1978. His first two appearances were due to his 1975 U.S. Amateur victory, and he was paired for the first round with defending Masters champion Jack Nicklaus.
His final invitation came because he had been a member of the 1977 U.S. Walker Cup team, which at the time meant a Masters invitation. Ridley remains the last U.S. Amateur champion who never turned professional.