Mohamed Noor shot Justine Ruszczyk Damond as she approached his patrol car to report a possible rape behind her Minneapolis home on July 15, 2017, BBC reported.
Damond, 40, was unarmed and the former policeman was found guilty of her murder on Tuesday.
Her family said they will donate $2 million toward fighting gun violence.
The mayor of Minneapolis, Jacob Frey, said unprecedented circumstances played a role in the settlement, which is the highest the city in the state of Minnesota has ever paid out.
"There was not a clear threat before the use of force was made," said Frey.
"This is not a victory for anyone, but rather a way for our city to move forward."
The Ruszczyk's attorney, Robert Bennett, said the family was quietly satisfied with the settlement.
It would send "an unmistakable message to change the Minneapolis Police Department in ways that will help all of its communities," he added.
Noor, 33, is the first police officer in the city's history to have been found guilty of murder for an on-duty shooting.
Damond, a yoga instructor from Sydney with dual Australian and US citizenship, had moved to the Midwestern city to marry her boyfriend, Don Damond.
She had adopted his surname ahead of their nuptials and they were due to marry a month after the shooting.
How was Damond killed?
Damond called 911 as she believed a sexual assault had taken place in the alley behind her home.
In court, Noor said he recalled seeing a blonde female in a pink T-shirt approach his squad car on the night of the shooting.
He said he opened fire because he believed there was an imminent threat after he heard a loud bang and saw Damond with her right arm raised.
Noor said his partner, Officer Matthew Harrity, shouted ‘Oh Jesus!’ and fumbled with his gun in its holster before ‘he turned to me with fear in his eyes.’
The defendant said he ‘had to make a split-second decision’ and shot Damond across his partner through the car window.
The trial heard the victim lay dying from a gunshot wound just over a minute after ending a phone conversation with her fiancé, Don.
She had told him that police had just arrived after she called them to report a possible sexual assault in the alley behind their home. No such attack was ever found to have occurred.
The death drew international criticism and Australia's Prime Minister at the time, Malcolm Turnbull, said it was ’inexplicable.’
Noor was handcuffed and taken into custody immediately upon being convicted by a jury on Tuesday of third-degree murder and second-degree manslaughter.
He was acquitted of the most serious charge of second-degree murder with intent to kill.
Noor told the court that upon realizing he had shot an unarmed woman he felt like his ‘whole world came crashing down.’
Prosecutors questioned whether the loud bang was real, pointing out that neither Noor nor his partner initially mentioned anything at the scene about hearing such a noise.
Damond's fingerprints were not found on the squad car, the court heard.
The fallout cost Janeé Harteau her job as Minneapolis' police chief and was a factor in the election defeat of the city's mayor at elections in November 2017.
Minneapolis Police Chief Medaria Arradondo apologized to Damond's friends and family in a statement released after Tuesday's verdict was read.
"This was indeed a sad and tragic incident that has affected family, friends, neighbors, the City of Minneapolis and people around the world, most significantly in her home country of Australia," he said.