"This has nothing to do with starting a new chapter," he told reporters. "I just wanted to. My father thought enough to give me his name, so why not?"
Upton will use his birth name this season after long going by B.J., short for Bossman -- his father Manny's nickname -- Junior. Upton's full name is Melvin Emanuel Upton.
Upton said Monday that most of his friends already call him "Mel or Melvin."
"Nobody really calls me B.J., except at the stadium," he said.
Upton is entering the third year of a five-year, $75 million deal with Atlanta, the biggest free-agent contract in Braves history.
He endured a nightmarish 2013 season in which he hit only .184, struck out in more than one-third of his at-bats and was benched. Last season, Upton hit just .208 with 12 homers and 35 RBIs.
The speedy center fielder will be three seasons removed from his last season with the Tampa Bay Rays, in which he belted a career-high 28 home runs while batting .246. He has a career .243 average.
Over the past three seasons, Stanton is averaging .277 with a .549 slugging percentage, up from .525 over the prior two seasons.
It won't be easy for Upton, who ranked among the lowest of every-day MLB players last season in several statistical categories. His .208 batting average was 146th out of 147 qualifying players, his OPS of .620 was 141st, and his strikeout percentage of 29.7 was 144th, according to ESPN Stats & Information.
"[Those years] are over with," Upton said, according to MLB.com. "They're gone, and I can't change them. So I just need to work to the future and get ready for this year."
The Associated Press contributed to this report.