The deal is pending a physical exam, a source said.
"You've got to have pitching," manager Bobby Cox said. "You could have the best hitting team in the history of baseball and you still may not get it done. We will feel confident now that whoever toes the mound on any particular night, we've got a good chance of winning."
With their late push for Lowe, the Braves succeeded in beating out the New York Mets, the other principal suitor for Lowe.
Lowe, 35, has a career 126-107 record in 12 seasons with Seattle, Boston and the Los Angeles Dodgers. He's averaged 208 innings the past seven seasons, and consistently has one of the highest ground ball-to-fly ball ratios in the game.
"We wanted get back to being a pitching team," Braves general manager Frank Wren said. "If we can do another couple of moves, we can get back to that point."
Longtime Atlanta mainstay John Smoltz agreed to a deal with Boston late last week and right-hander Tim Hudson, who is recovering from elbow ligament-replacement surgery, might not be available until the second half of the season.
It's also questionable whether Tom Glavine will return to the Braves in the aftermath of elbow and shoulder surgery.
"There's a lot of teams involved, especially when it comes to the free agents," Cox said. "There's always six or seven teams going to be disappointed when they don't land the guy. That's what happened up with Burnett and Rafael Furcal."
During the winter meetings, when it appeared that Lowe was looking for a five-year, $80 million deal, one Braves official said the club had "zero" interest in the pitcher.
Although the Mets had given indications they were willing to increase the money on their three-year, $36 million offer to Lowe, management was never comfortable with the idea of extending its offer to four years.
Jerry Crasnick covers Major League Baseball for ESPN.com. Information from The Associated Press was used in this report.