Kelly Clarkson made a couple's wedding day even more special, making a surprise appearance to sing "Piece by Piece" for their first dance.

The Stacy, the bride, and her groom were blindsided and overwhelmed by emotion when Clarkson and a live band were revealed from behind a curtain as they took the floor to dance together as husband and wife. Neither knew to expect the megastar, and Clarkson seemed tickled to be a gift for them.

She sang "Piece by Piece" — a song from Clarkson's point of view about how her husband, Brandon Blackstock, was there to pick up the pieces of wreckage done by the singer's father, who was absent in her life.

Clarkson grew emotional as she sang the personal lyrics. "It's hard to sing at a wedding," she admitted, laughing as the audience cheered her on in support. The singer shared after the performance that Stacy's sister, Tanya, set up the incredible surprise.

"They told me that you related to the song and I thought it might be a cool moment that you found somebody better than maybe what we were shown," Clarkson told the couple, greeting them on the dance floor with a hug. "I'm so happy for you. I hope that this didn't wreck your day. When they said it was a surprise, I freaked out!"

"Thank you so much, you made my day," Stacy replied tearfully as Clarkson told her how beautiful she looked and offered her congratulations to the happy couple on top of another hug.

Clarkson, a coach on The Voice, is in talks to host her own daytime talk show. The Hollywood Reporter details that Clarkson is filming a pilot for the show that could see a fall of 2019 debut. She married Blackstock in 2013.

7 More Truly Unforgettable Kelly Clarkson Moments