The pop singer tweeted a photo on Monday in her wedding gown next to Blackstock. She writes, "I'm officially Mrs. Blackstock."
Clarkson says she tied the knot on Sunday at Blackberry Farms in Walland, Tennessee, outside Knoxville.
A representative for the singer didn't immediately respond to an e-mail seeking comment about the marriage.
Clarkson was the first winner of American Idol and has released five albums and sung multiple pop hits. She has won three Grammy Awards.
Blackstock manages country star Blake Shelton.
The couple has been dating for two years and got engaged last year.
Kelly shared the following pics on Twitter:
Thnx Temperley 4 my beautiful dress! & thank you to my friend @JimVerraros & Maria Elena 4 the beautiful headpiece! pic.twitter.com/08FPoLloVw
— Kelly Clarkson (@kelly_clarkson) October 21, 2013
Another picture from our wedding :) pic.twitter.com/3YS2WjIpOD
— Kelly Clarkson (@kelly_clarkson) October 21, 2013
I'm officially Mrs. Blackstock :) We got married yesterday at Blackberry Farms in TN, the most beautiful place ever! pic.twitter.com/vYYqopBAcr
— Kelly Clarkson (@kelly_clarkson) October 21, 2013