The 32-year-old recording artist served more than five months on a probation violation charge and will remain on probation for two more years, E! Online reported.
Her manager and members of her family greeted her as she left the jailhouse Sunday morning.
"I'm so happy to be out," McCready said. "I'm the happiest girl in the world right now."
The singer had been incarcerated since July when she was arrested in Florida on charges of battery and resisting arrest, stemming from a domestic dispute with her mother, E! Online noted.
McCready was formally sentenced in September to a year behind bars as a result of the Florida arrest, which violated the terms of a 2004 drug arrest. At the time of her sentencing, the singer received credit for 75 days already served.
"Oh, my God, I'm gonna work," she said upon her release. "Work, work, work. And sing. And go see my son, who I've missed more than anything you can possibly imagine."
McCready's toddler son, Zander McCready, has been staying with the singer's mother.