Judge Nona Klippen announced her decision at the Santa Clara County Hall of Justice at 3:30 p.m. She dismissed the charges, citing insufficient evidence following his ex-girlfriend's testimony in which she admitted to making up the allegations against Foster.
The judge also reduced the weapons charge to a misdemeanor.
Last week, Foster's ex-girlfriend, Elissa Ennis, took the stand for nearly two hours during his preliminary hearing against the advice of her own attorney.
Ennis cried several times throughout her testimony May 17 and admitted to falsely accusing Foster of domestic violence because he had broken up with her. She said: "I was pissed and I wanted to end him."
RELATED: Judge to decide if 49ers' linebacker Reuben Foster will stand trial on domestic violence charges
Santa Clara County Sheriff's deputies and Los Gatos-Monte Sereno police were called out to Foster's home in Los Gatos on Feb. 11 after receiving multiple 911 calls from Ennis. She initially told investigators that Foster dragged her out of the house, threw her clothes outside and "punched her in the head 8 to 10 times," causing an eardrum to rupture, according to a police report.
In a blow to prosecutors, Ennis testified she made the entire story up as part of an extortion plot. She then claimed that she had actually been injured the night before the alleged beating during a fight with two women in San Francisco after a road-rage incident. Video of that altercation was turned over to the Santa Clara County District Attorney's office and was also presented by the defense as evidence during the preliminary hearing.
Ennis also stunned onlookers in court that day by admitting she had previously been arrested in Louisiana for filing a false domestic violence report against another ex-boyfriend in 2011 when that man tried to break up with her.
In addressing her initial accusations against the 49ers star, Ennis said, "I didn't think it would get this far."
VIDEO: 'I wanted him to go down' Reuben Foster's ex-girlfriend says she fabricated allegations
When Ennis was asked why she was putting herself at risk for perjury by recanting her claims of domestic violence against Foster, she said she wanted to do the right thing and help clear his name. Ennis also said she was going to check herself into a 'clinic' after the hearing for treatment on unspecified issues.
Regarding the felony weapon charge against Foster, which was based on a SIG Sauer 516 that was found inside his home the morning of the alleged beating, the defense asked the judge to reduce the charge to a misdemeanor. The rifle was purchased legally in Alabama, where Foster played football for the University of Alabama, but is illegal to possess under California law.
Foster's future with the 49ers hinged on what happened with the domestic violence charges.
Foster remained free on $75,000 bail. He previously pled not guilty on May 7 to felony domestic violence.
Chris Nguyen will have a full report on ABC7 News at 5 p.m. and 6 p.m. And you can follow him on Twitter for updates on this developing story.