Freeman, 21, also led all Major League rookies with a .433 on-base percentage in 27 July games, while pacing NL rookies with six homers and 17 runs. His 18 RBIs tied for the most in the NL among rookies.
He added seven doubles and a .600 slugging percentage.
"It's just another month closer to where we need to be," Freeman said. "It's a great honor, obviously. I'm truly honored to be named that, but we need to win games."
Freeman hit safely in 23 of those 27 games, including each of the last 15 during the month. He is currently riding a career-best 18-game hitting streak, the longest by any rookie in the Majors this season.
He has reached base in 40 of his last 44 games dating back to June 16.
"Freddie's really finally comfortable, and you're starting to see the kind of at-bats that middle-of-the-lineup guys have. And he's 21," said Braves third baseman Chipper Jones.
On July 4 against the Rockies, Freeman recorded his first career multihomer game, going 2-for-3 with three RBIs in a 4-1 victory. He drove in another home run the next day and recorded his first walk-off hit in a 9-8 win against the Nationals on July 17.
He collected 10 multihit games during the month, including three consecutive three-hit games from July 26-28.
Freeman entered Wednesday leading all NL rookies in batting average (.296), hits (116), doubles (26), walks (39) and extra-base hits (41) this season, while ranking second in multihit games (30) and homers (15).
Joey Nowak is a reporter for MLB.com. Follow him on Twitter at @joeynowak. Associate reporter Steven Miller contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.