The 37-year-old Braun, a six-time All-Star selection, hasn't played this season after becoming a free agent when the Brewers declined to exercise a $15 million mutual option in his contract in October.
"I have weighed this decision for many months," Braun said in a video posted to social media. "While I still love this game very much, the time is right for me to retire from my playing days.
"It's difficult to describe my emotions today, but it starts with overwhelming gratitude to those who have shared this experience with me while offering their unconditional support at every turn. ... I will forever appreciate the best fans in the game and the countless people who came out to the ballpark night after night, making Milwaukee the greatest city to play the game."
Braun played all 14 of his MLB seasons in Milwaukee, bashing 352 career home runs during that span. He ranks second in club history in career RBIs (1,154), extra-base hits (809), total bases (3,525) and doubles (408).
The five-time Silver Slugger Award winner also ranks third in runs (1,080), hits (1,963), triples (49), stolen bases (216) and walks (586).
"I am so fortunate to have enjoyed a 14-year career wearing the jersey of one team, and even more grateful that team is the Milwaukee Brewers," Braun said. "I am retiring today from Major League Baseball, but my love for all those who supported me continues to grow.
"I cherish great memories from my time with the Brewers and will continue to build on the many friendships made in this amazing city."
Braun had a career-worst .233 batting average with seven home runs and 27 RBIs over 39 games last season while battling a back issue. His back problems prevented him from playing in the Brewers' first-round playoff series against the eventual World Series champion Los Angeles Dodgers.
Braun proved to be one of baseball's best hitters from 2007-12, but he never regained that form after he was suspended halfway through the 2013 season for taking performance-enhancing drugs. The veteran slugger later acknowledged that he used banned substances while rehabilitating an injury and apologized.
The Brewers are honoring Braun with an on-field ceremony Sept. 26.