Noted orthopedic specialist Dr. James Andrews operated on Favre at the Andrews Institute in Gulf Breeze, Fla., where Favre and his agent Bus Cook were spotted by a handful of people.
Favre confirmed the procedure on his website.
"This is to confirm that I did have a procedure to remove some scar tissue and bone spurs from my ankle which had been bothering me for a period of time. I appreciate your concerns," Favre's statement read.
Dr. Andrews cleaned up scar tissue and other elements of the joint to allow Favre a better range of motion.
A source close to Favre said the 40-year-old signal-caller would likely need four to six weeks of rehabilitation before beginning a running program that would put him on schedule to report to training camp "either at the beginning of camp or shortly thereafter."
Favre had previously said he would need the surgery if he were going to play in 2010.
In assessing his physical readiness to play football while recovering from shoulder surgery last summer, Favre mentioned he was having problems with his left ankle.
"I've had surgery [on my] left ankle twice and need it again," Favre said at the time. "I can barely move the ankle up and down. Walking on it feels like I have glass in my shoes and running is way harder than it needs to be.''
Favre, who turns 41 in October, is coming off one of the best seasons of his storied career, throwing for 33 touchdowns and only seven interceptions while guiding the Vikings to a 12-4 record. He is under contract for $13 million next season if he plays.
The surgery came one day after Favre visited the Southern Mississippi baseball team in Hattiesburg, Miss., and told the Golden Eagles he would return for one more season in the NFL if they made it to the College World Series for the second consecutive year.
Chris Mortensen is ESPN's senior NFL analyst. ESPN's Ed Werder and The Associated Press contributed to this report.