However, a third has been charged with endangering her neighbours.
Attorney General Daniel Cameron announced the Louisville grand jury's decision at a news conference on Wednesday as protesters against racial injustice and police brutality massed in the streets of Kentucky's largest city.
Former Detective Brett Hankison was indicted on three counts of wanton endangerment in the first degree, an offence that ranks at the lowest level of a felony crime in Kentucky and carries a maximum sentence of up to five years in prison.
Benjamin Crump, a civil rights lawyer representing the Taylor family, said it was "outrageous" that none of the officers would be criminally charged with causing Taylor's death.
Taylor (26) was killed in front of her armed boyfriend shortly after midnight on March 13 this year inside her Louisville apartment after Hankison and his two colleagues forced their way in with a search warrant.
The two other officers, Sergeant Jonathan Mattingly and Detective Myles Cosgrove, were not charged because they were justified under Kentucky law in returning fire after Taylor's boyfriend, Kenneth Walker, shot at them, wounding Mattingly in the thigh, Cameron said.
"There is no doubt that this is a gut-wrenching, emotional case," Cameron, a black Republican, said at a news conference.
Governor Andy Beshear called on Cameron to release all evidence in the case so that the public could better understand the outcome of the investigation.
"Everyone can and should be informed," Beshear said. "Those feeling frustration, hurt - they deserve to know more."
Hankison fired his weapon 10 times. Some of the bullets traveled through Taylor's apartment into adjacent Apartment No 3, where a man, a pregnant woman and a child were at home.
There was "no conclusive" evidence that any of Hankison's bullets struck Taylor, Cameron said. The grand jury indicted him for wantonly placing the neighbors in danger," Cameron said.
Organizers of the protests against police brutality that have become a daily occurrence expressed frustration at the outcome.
"Tonight, tempers may flare," community organiser Reece Chenault (40) said. "People are going to be sad, and I think you are going to see a lot of tears with folks who are marching."
Hundreds of protesters wound their way out of downtown Louisville's Jefferson Square Park and marched through the streets chanting, "Out of the homes, into the streets!" Local television news footage showed police in riot gear and face shields forming into lines.
'WANTON MURDER,' LAWYER SAYS
"If Brett Hankison's behavior was wanton endangerment to people in neighboring apartments, then it should have been wanton endangerment in Breonna Taylor's apartment too," Crump said. "In fact, it should have been ruled wanton murder!"
Ahead of the announcement, Louisville Mayor Greg Fischer announced a 72-hour curfew for the city beginning at 9 p.m. "I urge everybody to choose peaceful and lawful protest," Fischer said.
Despite having a warrant that allowed them to enter the premises unannounced, the three officers involved in the raid knocked on Taylor's apartment door and announced their presence outside, which was corroborated by a neighbour who witnessed the arrival, Cameron said. Getting no answer, they "breached the door," he said.
Mattingly entered first, and at the end of a corridor saw Taylor and her boyfriend, Kenneth Walker, with Walker pointing a gun.
Walker fired, injuring Mattingly in the thigh. Mattingly returned fire, and his colleagues began shooting soon after, Cameron said. Hankison fired 10 bullets, Cameron said.
Six bullets struck Taylor, he said, contradicting reports she had been hit five times. Ballistics investigators found only one shot, fired by Cosgrove, was fatal, Cameron said, adding that medical evidence showed that she likely died from that bullet "within a few seconds to minutes."
In June, the Louisville Metro Police Department fired Hankison with interim Police Chief Robert Schroeder writing that Hankison "displayed an extreme indifference to the value of human life" when he "wantonly and blindly fired" into Taylor's home.
The department reassigned Mattingly and Cosgrove to administrative duties.
In obtaining a warrant as part of an investigation of a drug ring, police told a judge they believed that one of the men suspected of selling drugs had used Taylor's apartment to receive packages.
Taylor had previously dated a suspected drug seller but had severed ties with him, according to her family.
She and Walker were in bed when police broke down her door with a battering ram shortly after midnight, the families' representatives have said.
Louisville has agreed to pay $US12 million (NZ$18 million) to Taylor's family to settle a wrongful-death lawsuit, Mayor Fischer announced earlier this month.
