The singer posed for a selfie with the royal, who was at Sunday's big game.
Guyton sang the national anthem at this year's Super Bowl, while Harry attended the big game at Sofi Stadium in Los Angeles with his cousin, Princess Eugenie. The 38-year-old country singer tweeted a picture of her with Harry, rocking a red-and-white track suit while a masked-up Harry also kept it casual in jeans, a T-shirt and a blazer.
"I met Prince Harry. He was just lovely," Guyton wrote. "I even curtsied in my track suit."
ET spoke to Guyton at CMT Crossroads where she described the meeting with Harry.
"It was crazy. My parents actually met him first and took pictures of him the suite and were like 'man, does anyone tell you, you look like Prince Harry?' And he took off his hat to reveal his hair and she still didn't get it until I was up in the suite and said that was actually Prince Harry. It was crazy," she recalled of her run-in with the royal.
Harry, 37, kept a low-profile at the big game as he sat with 31-year-old Eugenie. The royals' significant others -- Meghan Markle and Jack Brooksbank -- were not in attendance.
Meanwhile, ET spoke with Guyton about singing the national anthem at this year's Super Bowl where she shared just how much the major moment meant to her.
"Being out there, it was a moment for me...it was a God moment." Guyton explained. "When you work for something so hard, never in a million years did I think I would do that."
Ahead of the game, Guyton told us it wasn't an honor she wasn't taking lightly.
"You know, I have been wanting to do music for song long and to be able to stand on this stage on this day," she said. "There's so much division in this country and there’s so much that is happening, it’s hard. This is a moment that I get to be that Black girl from Texas that gets to stand on that stage and sing and hopefully unite the country. I'm going to have a choir behind me and it’s all the faces of America. This is the America that I would be proud to wave my American flag emoji for."