Hart, who had previously found success as the general manager of the Indians and later served that role with the Rangers, had served as the Braves' president of baseball operations since the end of the 2014 season.
His future with Atlanta had been uncertain since Oct. 2, when former general manager John Coppolella and the club's top international scout Gordon Blakeley resigned in the midst of MLB's ongoing investigation of alleged infractions committed in relation to the domestic Draft and the signing of international prospects.
"This was a difficult decision, but it's one that I made with the best interests of the Atlanta Braves in mind," Hart said in a statement. "With the hiring of Alex Anthopoulos as general manager, this organization is in great hands. I believe that the talent of the Major League players, combined with the young talent soon to arrive, makes the Braves poised for a great run of success.
"This is a good time to step aside and let Alex and his group put their stamp on this great franchise. I still have a tremendous passion for this great game, and I plan to stay active and contribute to the game.
"I want to thank Braves fans -- the best fans in baseball -- for your patience during this rebuilding time. You will soon see the winning team that you deserve.
"I also want to thank my beautiful and supportive family. I am very excited to see how the next chapter of our life unfolds.
"Finally, I want to thank my longtime friend, John Schuerholz, for convincing me to come to Atlanta to oversee the rebuild, and especially to our leader, Terry McGuirk, who has shown such passion for returning to a winning place. Thank you all, and go Braves!"