The Kelly Clarkson song that made everyone cry

Kelly Clarkson. Photo/AP

Kelly Clarkson brought everyone to tears as she sang Piece by Piece on American Idol.

The 33-year-old star - who shot to fame when she won the first series of the programme in 2002 - sobbed during the performance and made judges Jennifer Lopez and Keith Urban cry too, during a special appearance on the 15th and final season of the talent show last night.

And afterward, show host Ryan Seacrest praised Kelly - who is pregnant with her second child - for the "incredible" and emotionally charged performance.

Kelly replied: "I'm pregnant and it's nostalgic and I can't believe it's the last season. Yeah, really sorry I just bawled."

The song has a strong meaning to the star - who already has 19-month-old daughter River Rose with husband Brandon Blackstock - and she previously revealed she wrote it as a homage to Brandon's great parenting.

Kelly even missed the Grammy Awards - for which she was up for Best Solo Performance for Heartbeat Song and Best Pop Vocal Album for Piece by Piece - to sing Piece By Piece on the talent show and be a guest judge for the episode, because doctors said she had to take rest and cut down on work.

Speaking recently, the Breakaway singer said: "I was going to do the Grammys and Idol, and then my doctor was kind of like, I just have such hard pregnancies, flying back and forth to LA, like if they were closer together, I would've done both, but I had to kind of choose one.

"I obviously chose Idol because it's ending and I was the original winner, so it'd kinda be weird if I wasn't there."

- Bang! Showbiz