The cause of death "appears to be a single self-inflicted gunshot wound," the Cleburne County Sheriff's Office in Arkansassaid in a statement.
Deputies were called to a home in Heber Springs, Ark., Sunday afternoon, the statement said, and found McCready's body on the front porch. Family members have been notified and an autopsy will be performed.
NBC News has reached out to the singer's publicist for comment.
McCready had a No.1 country hit in 1996, when she was just 21, with "Guys Do It All the Time." Her other popular songs included "Ten Thousand Angels" and "A Girl's Gotta Do (What A Girl's Gotta Do)."
The singer, who has dated such famous men as "Lois and Clark" star Dean Cain and Red Sox pitcher Roger Clemens, has had more problems than hits in recent years.
Her relationship with Clemens made headlines in 2008. McCready told "Inside Edition" that she was just 16 when she met the married Clemens, but said their relationship did not become sexual until years later. Clemens issued a statement saying only, "I have made mistakes in my personal life for which I am sorry."
2010, she appeared on "Celebrity Rehab with Dr. Drew" seeking help for her battle with substance addiction.
In 2011, McCready's mother reported that the singer and her young son Zander were missing. McCready's mother was Zander's legal guardian. The singer returned her son by order of a judge. She gave birth to another son, Zayne, in April 2012.
In January, her boyfriend David Wilson died of a gunshot wound in his Heber Springs home. Wilson later appeared on TODAY and called Wilson her "soulmate." When asked by NBC's Andrea Canning if she shot Wilson, McCready replied, "Oh, my God, no. He was my life. We were each others' life."
Authorities are still investigating Wilson's death and have not named McCready as a suspect.
On Feb. 6, McCready's publicist said the singer was admitted to an inpatient facility, though the cause was not specified. Her two sons were placed in foster care while McCready was being treated.