Kelly Clarkson is officially off the market. Just days after filing for a marriage license, the singer wed longtime boyfriend Brandon Blackstock during a ceremony Sunday (Oct. 20) in the Great Smoky Mountains of East Tennessee.

"I'm officially Mrs. Blackstock :)," Clarkson tweeted Monday morning. "We got married yesterday at Blackberry Farms in TN, the most beautiful place ever!"

Blackstock is the stepson of country star Reba McEntire. His father, Narvel Blackstock, is Clarkson's manager.

A small group of family and friends were in attendance for the ceremony held at the luxurious Blackberry Farms, although months ago Clarkson admitted an elopement was a likely possibility. Since Blackstock happens to be Blake Shelton's manager, both he and his bride have demanding schedules.

Now that the wedding is over, Clarkson feels like she made the right decision.

"It sounds so cheesy, but I just didn't think I could be this happy," she said. "And I'm so happy, it's hard not to smile sometimes. It's so goofy."

The singer is especially proud of her custom-made wedding ring.

"[Brandon] did such a great job," said Clarkson. "It's like a replica of this Janis ring that I can't take out of England, but he made a replica for me."

October is turning out to be a monumental month for the newlywed singer, who will also release her first holiday album on Oct. 29. A special preview of Clarkson singing the timeless classic "White Christmas" has been released in promotion of the 14-track project.

For more, tune in to CMT Hot 20 Countdown this Saturday and Sunday (Oct. 26-27) at 11 a.m. ET/PT.