Freeman, who was placed on the 10-day disabled list on Thursday, sustained the injury after being hit by a fastball from Toronto Blue Jays left-hander Aaron Loup in Wednesday's interleague game. The 27-year-old slowly walked toward the dugout with his head down after being hit by the pitch.
Initial X-rays were inconclusive, but MRI and CT scans on Thursday revealed that Freeman sustained the second significant wrist injury of his young career. The two-time All-Star missed considerable time in 2015 while dealing with a right wrist injury.
"It's a tough blow. It wasn't the news I wanted to hear," Freeman said. "I had a feeling, but I was hoping for the best.
"It was just one of those pitches that got away. There was no intent. He was just trying to get me out."
Freeman was off to the best start of his career, batting .341 with a National League-best 14 homers and 25 RBIs in 37 games. He is hitting .290 in his career with 152 homers and 540 RBIs in 946 contests.
"When the best hitter in the game goes out, it really (stinks)," Braves starter Mike Foltynewicz said following Wednesday's 8-4 victory over Toronto.
Atlanta also signed veteran first baseman James Loney, who has a .284 career average over 11 seasons with the Los Angeles Dodgers, Boston Red Sox, Tampa Bay Rays and New York Mets. Loney hasn't played any major league games this season and was released by the Detroit Tigers earlier this year.
The Braves also recalled infielder Rio Ruiz from Triple-A Gwinnett in a corresponding move on Thursday. Ruiz, who made his major league debut after playing in five games in 2016, is batting .262 with four homers and 16 RBIs in 37 contests with Gwinnett this season.
Ruiz is playing third base on Thursday with Jace Peterson moving to first base.