The brothers combine with Jason Heyward, who won a Gold Glove in 2012, in an outfield potentially packed with power and speed.
"If we push ourselves to the next level, I feel with the extra push from each other there's no question we can be the best outfield in baseball," Justin Upton said in a telephone interview. "I'm not going to give us that label until we prove it."
The Braves, who also get third baseman Chris Johnson, are giving up one of their top pitching prospects, Randall Delgado, and three minor leaguers in the deal.
They are right-hander Zeke Spruill, shortstop Nick Ahmed and first baseman Brandon Drury.
Prado, projected to play third base for the Diamondbacks, can become a free agent after this season, but Arizona general manager Kevin Towers said he already was working with Prado's agent on a long-term deal.
B.J. Upton, 28, signed a five-year, $75.25 million contract with Atlanta in November.
Justin Upton, 25, said he already got tips from his brother from afar. Now there will be more chances for the two to help each other.
"I think from that standpoint it will be good, but I think more than anything being able to show up at the ballpark genuinely excited every day and have that energy," he said. "The more energy you can bring from the start every day, it makes you a better player."
Braves general manager Frank Wren said he expects the brothers will push each other.
"I do think it will drive them," Wren said. "We've been looking for that young dynamic, right-handed, power-hitting outfielder that can hit in the middle of the lineup and makes that other team think a little bit."
Who went where
• Braves get Justin Upton and Chris Johnson.
• The Diamondbacks get Martin Prado, top pitching prospect Randall Delgado and three minor leaguers.