The country singer is incredibly successful

Carrie Underwood has had an incredible career to date, which has seen her pick up countless awards over the years.

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The country star first came to the public's attention on back in 2005, and she's remained loyal to the show ever since.

This year, for the program's 20th anniversary, Carrie returned as a guest judge on Sunday night's episode, and it was the news that fans had been waiting for.

VIDEO: Carrie Underwood's love story with Mike Fisher

The official American Idol Instagram account revealed their joy in an upbeat post ahead of the show, writing: "We've been waiting all week for 8x Grammy winner and guest mentor @CarrieUnderwood, TONIGHT on American Idol."

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Carrie's fans were quick to comment on the post, with one writing: "Can't wait, that show changed her life," while another wrote: "I'm so excited to watch Carrie on the show." A third added: "Welcome back Carrie!"

The singer was just as thrilled to return, and wrote on her own account before the show aired: "I was honored to be able to come back and mentor the Top 5 contestants on @americanidol! Watch tonight at 8/7c on @abcnetwork."

Carrie Underwood returned to American Idol on Sunday night

The show made sure to properly pay tribute to the award-winning star with a Carrie Underwood-themed program.

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The top five contestants performed twice - with a Carrie Underwood song, and another song of their own choosing.

The show ended in shock after Fritz Hager and Nicolina Bozzo, who were both seemingly frontrunners, were eliminated at the end of the night. Carrie was just 22 when she appeared on the show, which skyrocketed her to stardom.

The award-winning star started her career on American Idol

During the 2005 series, judge Simon Cowell didn't hold back on what he thought of the singer, once telling her: "I will make a prediction. Not only will you win this show, you will sell more records than any other previous Idol winner."

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Carrie to date has sold the most records of any American Idol alum, with her first album, Some Hearts, selling 7.5million copies alone in 2005.

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