In an exclusive interview with The Associated Press ahead of Monday's announcement, the 21-year-old from Leesburg, Ga., said he was excited to visit the nation's capital for the first time. Phillips, a bluesy guitar man, said he's been focused on recovering from a serious kidney surgery since "Idol's" finale in May.
Phillips has revealed he was in crippling pain from a kidney blockage that made it hard to stand at times during parts of the "Idol" season and was undergoing a series of surgeries during breaks in the competition. His right kidney wasn't functioning properly, he said, but it didn't require a transplant.
Phillips hasn't performed since his "Idol" victory. Instead, he's been focused on recovery.
"I'm getting better each day, so that's a good thing. I'm just walking around, getting my strength back together," he said in an interview from Los Angeles. "It was tough, you know, those first few days, but I'm getting to where I can pick the guitar back up and write a little bit."
His travels to California and soon to Washington are the farthest Phillips has ever traveled from his Georgia home, he said.
The singer's best memories from "Idol" are the friendships he made, which he hadn't expected, he said. And being on stage for the first time is something he'll never forget.
"You know, I was so scared to death and, in the end, not knowing if I was going to puke before I went on stage," he said. "It was just terrifying. I get terrified every time, but that was just huge."
In Washington, Phillips will perform his hit single "Home" for an expected audience of more than 300,000 from the lawn of the U.S. Capitol before the annual fireworks. The show is broadcast live on PBS and NPR.
Phillips will join Matthew Broderick, country singer Josh Turner, "Smash" star Megan Hilty, composer John Williams, U.S. Olympic athletes and others at the concert, along with the National Symphony Orchestra.
"It's probably the biggest thing I've ever done besides 'American Idol,'" he said. "I'm just excited to get out there and do my first real live performance since everything that's been going on."
While in the nation's capital, he won't have much time to look around, but he can always come back to play tourist. Soon he'll be starting the "American Idol" tour and heading into the recording studio to turn out an album as quickly as possible.
"It's going to be a busy, busy summer," he said.