The couple have been together for nearly seven years and share two young children, daughter River, 5, and son Remington, 4.
The split comes a little over one month after Clarkson reportedly listed the couple's Los Angeles mansion on the market for nearly $10 million.
Blackstock, a former country music manager, now reportedly works on "The Kelly Clarkson Show." Blackstock is the stepson of country superstar Reba McEntire, who has performed with Clarkson numerous times.
Clarkson married Blackstock in 2013 after meeting him at a rehearsal for the Academy of Country Music Awards in 2006, People reported. The star was on hand to sing a duet of “What Hurts the Most” with Rascal Flatts. Blackstock was the group’s tour manager at the time.