Underwood performed at halftime of the 2006 Thanksgiving Day football game at Texas Stadium in Irving, TX and was friends with Dallas Cowboys quarterback Tony Romo. She attended his birthday party in April 2007, and on May 15, 2007, he escorted her to the Academy of Country Music Awards.

Since August 2007, she had been dating Chace Crawford of Gossip Girl fame. On October 4, 2007, People magazine reported that the two were seen holding hands in New York City. Though according to recent reports, the two have recently broken up for good.

In October of 2007, Underwood created a Swarovski Crystal encrusted jean jacket for the SOS Children's Villages - USA "World Orphan Week". The jacket sold for more than $700.