The Jays only said they were unable to come to terms on a contract with Seitzer, who was appointed Oct. 31, 2013. But the Braves made it official Monday, announcing Seitzer is replacing Greg Walker as their hitting coach.
Seitzer said he didn't receive a 2015 contract offer from the Jays until "maybe a week ago." He said he received permission to call the Braves when he couldn't reach a financial agreement with Toronto.
The 52-year-old Seitzer, who has also served as hitting coach for the Royals and Diamondbacks, becomes the Braves' fourth hitting coach in six seasons.
The Jays are bringing back bench coach DeMarlo Hale, pitching coach Pete Walker, first-base coach Tim Leiper and third-base coach Luis Rivera to work under manager John Gibbons.
Bullpen coach Bob Stanley has accepted another position within the organization.
Gibbons gave his entire coaching staff a vote of confidence on the final day of a season that saw his team finish third in the AL East with an 83-79 record.
"I will say it's a hell of a coaching staff," Gibbons said. "It's a good group of individuals, very good baseball guys, and I thought they did a tremendous job. Good, hard-working staff."
The Jays ranked fourth in the American League and eighth in the majors with a .259 hitting average in 2014. The previous year, Toronto hit .252 to rank 10th in the AL and 15th in the majors.
The Braves hit .241 in 2014, 11th in the National League and 26th in the majors.
A former all-star third baseman, Seitzer hit .295 in 12 major league seasons with the Royals, Milwaukee, Oakland and Cleveland.
"I feel like God gave me a gift to be a hitting coach more than He gave me a gift to be a player," he said.
Atlanta also named Jose Castro as assistant hitting coach.
Castro, 52, was the Cubs' quality assurance coach this season. He was Seattle's interim hitting coach in 2008 and has worked as a minor league hitting co-ordinator and coach in the Montreal, Florida, San Diego and Seattle organizations.
Braves manager Fredi Gonzalez said he hopes to utilize Chipper Jones as a hitting consultant. Jones, who retired after the 2012 season, said he wasn't ready to take on a full-time coaching job when approached by the Braves.
"It's something that Kevin and Jose are going to have to talk to Chipper about, but I want to see Chipper around this ballpark a lot more than we saw the last two years," Gonzalez said.
Greg Walker resigned after the Braves finished 14th in runs scored among National League teams, ahead of only San Diego.
With files from The Associated Press