"We've been fighting for the children in our community, particularly those children who were deprived by this cheating scandal," Fulton County District Attorney Paul Howard said.
Ten of the defendants were taken into custody, while one woman who is pregnant will remain out on bond until sentencing.
All 11 were convicted of racketeering, with a mixture of convictions and acquittals on other charges, including making false statements, CNN affiliate WGCL reported
. One teacher was acquitted of all charges.
The convicted defendants comprised three executive administrators, one principal, one assistant principal, four teachers and two testing coordinators.
Howard told reporters sentencing should happen in the coming weeks.
The penalty for racketeering is five to 20 years, while make false statements can be punishable by up to five years in prison.
Defense lawyers were upset that Fulton County Superior Court Judge Jerry Baxter sent their clients to jail while awaiting sentencing. One attorney told the judge that none of them have criminal records and they all had significant ties to Atlanta.
Baxter, clearly upset by the requests, said: "They have been convicted of felonies, serious felonies."
CNN affiliate WSB reported
that defense attorneys were nearly all stunned by the verdicts.
"If you were there for the seven or eight months that we were there (at trial), and you saw the evidence and you saw the witnesses who testified -- convicted folks, liars, people who admitted they lied, who got deals. And that was the evidence against our client? You'd be as surprised as we are," attorney Keith Adams told the station.
The Atlanta Board of Education said changes began with new leadership under Superintendent Meria Carstarphen
"Reforms began almost three years ago and additional ones have been created under this new leadership to make sure something like this never happens again," the board said in a written statement. "Challenges remain, for sure, but we are making progress every day and there is great reason to be optimistic.
Cheating began in 2001
In 2013, a Fulton County grand jury indicted 35 educators from the district, including principals, teachers and testing coordinators.
More than 20 former school system employees took a plea deal, WGCL reported.
A state review had determined that some cheating had occurred in more than half the district's elementary and middle schools. About 180 teachers were implicated initially.
The cheating is believed to date back to early 2001, when scores on statewide skills tests began to turn around in the 50,000-student school district, according to the 2013 indictment.
For at least four years, between 2005 and 2009, test answers were altered, fabricated and falsely certified, the indictment said.
More than 250,000 answers changed
Michael Bowers, a former Georgia attorney general who investigated the cheating scandal said in 2013 that there were "cheating parties," erasures in and out of classrooms, and teachers were told to make changes to student answers on tests.
"Anything that you can imagine that could involve cheating -- it was done," he said at the time.
During his investigation, he heard that educators cheated out of pride, to earn bonuses, to enhance their careers or to keep their jobs, he said.
The District Attorney's office said more than 250,000 wrong answers were changed.
During the seven-month trial, prosecutor Fani Willis told the jury that some students were given the correct answers, WSB reported.
Investigations into the remarkable -- and suspicious -- improvements on standardized tests were first reported by The Atlanta Journal-Constitution newspaper in 2008.
Beverly Hall, the superintendent of Atlanta Public Schools who resigned in 2010, was too ill to go to trial; she died in March. Hall repeatedly denied any direct knowledge of wrongdoing.
Another woman who was indicted died in September 2013.