David Mueller has accused Swift of slandering him to his radio station, alleging her complaint led to his unfair dismissal.
Swift is counter-suing Mueller in the civil case, alleging he groped her during a 2013 backstage photo op with fans and guests before a concert in 2013.
US District Judge William Martinez ruled that Swift could not be held liable because Mueller failed to prove that she personally set out to have him fired.
He agreed with Swift’s attorney, who had filed a motion asking for the pop star to be dropped from Mueller’s lawsuit, saying his case should have been against his Colorado radio station.
Swift was happy to hear the judge’s ruling in court, hugging members of her legal team.
Mr Martinez said the eight-person jury will make a decision on Swift’s claim that she was groped.
The panel will also consider allegations from Mueller that Swift’s mother, Andrea Swift, and her radio manager, Frank Bell, contributed to him losing his job.
Swift’s attorney Doug Baldridge had argued there was no evidence the singer herself took any action that harmed Mueller.
“A man grabbed her rear end. She told her mother, and that’s it,” Mr Baldridge said.
Earlier Friday, Swift’s former bodyguard Greg Dent testified that he witnessed the singer’s skirt being flipped up as she posed for a photo with Mueller and his girlfriend.
Mr Dent, a former police officer, said in his testimony: “I saw his hand under her skirt… Her skirt went up… She jumped.”
Swift spent an hour on the witness stand on Thursday, defiantly recounting what she called a “despicable and horrifying and shocking” encounter.
“He stayed attached to my bare ass-cheek as I lurched away from him,” she said.
“It was a definite grab. A very long grab.”
Mueller gave evidence on Tuesday to say he may have made innocent physical contact with Swift, but insisted he did not grope her.
Asked if he grabbed her backside, he replied: “No, I did not.”