Prosecutors were able to ask for a charge of capital murder because the victim was under 10.
In a statement, it said investigators identified Black as a suspect after receiving a tip.
Prosecutors and a lawyer for Jazmine's family, S. Lee Merritt, named the second suspect as Larry Woodruffe, 24, who is also black and was at the Harris County jail on Sunday on a drug possession charge. The sheriff's office did not elaborate.
Police say there is another suspect involved.
Houston Mayor Sylvester Turner said the support Jazmine's family received provided law enforcement "with a sense of urgency and made Jazmine's loved ones know they weren't alone in their time of grief".
It's been nearly a week since the 7-year-old was shot in the head by a passing motorist while riding in her mother's auto along with her three sisters.
It is somewhat unclear how the initial report of a white shooter led to the arrest of two black men.
It comes as hundreds of people gathered at a rally on Saturday holding signs reading 'Justice for Jazmine'.
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According to authorities, Black admitted to driving the auto used in Barnes' Dec. 30 shooting after he was arrested during a traffic stop in a different vehicle. Her mother, LaPorsha Washington, who was also injured in the shooting, vowed then that the gunman would be found.
Campaigners had feared the shooting, on an African-American family, may have been racially motivated. The description of a white man viciously gunning down a black child set off a firestorm.
A $100,000 reward has been offered to anyone with knowledge of the shooting.
Regardless of any confusion, the family "wanted the right person to be convicted - not a white person", Merritt said.
At a court hearing early Sunday, prosecutors said a confidential source had contacted the sheriff by email and told him the killers had "shot the auto by mistake", thinking the vehicle was someone else's that they had seen earlier that night.
Washington thanked everyone who came to honor her daughter, whose birthday is next month, she said.
On Thursday, sources close to the family told KPRC2's Brandon Walker that O'Neal and Houston Senior Police Officer Kenneth Miles dropped off a cashier's check to cover the costs of Jazmine's funeral, which is scheduled for noon Tuesday at Green House International Church on West Greens Road.
"I'm telling you, every time I see one of y'all reach out for me, I can hold my head up", Washington was quoted by CNN as saying.
Another athlete, DeAndre Hopkins of the NFL's Houston Texans, pledged his playoff game check to Jazmine's family last week. Her funeral is at noon. He said Black admitted to having a role in Barnes' death.