Mize's father, Charles, read letters written by Masters greats to his son as he was recognized at the 13th annual Mayor's Masters Reception, held at Augusta Common.
In a letter, Jack Nicklaus, who won his sixth and final Masters the year before, recalled Mize's legendary 140-foot chip shot to win the 1987 tournament as "one of the most famous and exciting in Masters history."
Two-time Masters champion Ben Crenshaw called Mize one of "golf's kindest gentlemen."
Before presenting Mize with a crystal key to the city, Mayor Deke Copenhaver reflected that he and Mize had grown up on the same street, as had two of the three members of country music group Lady Antebellum.
Mize, who worked the third-hole scoreboard at Augusta National Golf Club as a teen, said winning the Masters was "a dream come true. I'm a very blessed man."
Wayne Hawkins, the chairman of the Mayor's Masters Reception Committee, said Mize was an easy selection for the honor.
"We've been trying to work Larry in," Hawkins said at a VIP reception before the event.
The gathering at Augusta Common, one of the few Masters Week golf events open to the public, attracted more than 1,000 people, including about 90 wounded warriors, who were special guests.
"This is our night to kind of let everybody experience Masters Week," said Staff Sgt. Brett Althoff, who attended with the injured soldiers. "It's something they'll be able to cherish for a lifetime."
Ike Branch stopped by on his way home from work and said he enjoyed the event.
"I'm impressed with the crowd," said Branch, of Evans.