"Where does the time go," the singer wrote on Instagram. "Please enjoy a page from the journal of a 22-year-old farm girl who just had the most incredible night!"
The journal entry tells the story of the final moments before Ryan Seacrest announced her win on May 25, 2005.
"It came down to this final moment. Ryan had the gold card in his hand," young Underwood wrote. "Oh yeah, I forgot to mention that they presented us with keys to 2 identical red convertible 2005 Mustangs! How cool is that? Anyways, back to the story. Big moment. I took one more look at the amazing crowd and let it sink in for a few seconds. Ryan said something like, 'And your 2005 American Idol is…' My heart beat fast and I closed my eyes. CARRIE UNDERWOOD!!! The crowd went wild. I immediately started crying. It was a beautiful moment. All the other contestants were sent out to hug me. I was crying the whole time. Then I was asked to sing. I blubbered through 'Inside Your Heaven.' Pyrotechnics went off behind me."
Underwood won the fourth season of the iconic reality singing competition, beating runner up bo Bice. The win scored her a recording contract with 19 Recordings/Arista Records and she released her Some Hearts album that same year. The release sold over seven million copies, making her one of American Idol’s most successful alumni in the show's 20-season history. She’s since released nine more albums and won her eighth GRAMMY Award last year.
Her newest album, Denim & Rhinestones, comes out next month.