The former pub singer put his face to his hands and hugged mentor Dannii Minogue upon hearing the news, before crossing the stage to embrace runner-up Rebecca Ferguson.
Rendered virtually speechless by his win, Cardle eventually declared: "I just want to say thank you so much from the bottom of my heart for voting for me.
"And congratulations to everyone who got to this stage because everyone should be so proud. I want to thank all the judges, Dannii especially."
Cardle was then handed a hard copy of his winner's single - Biffy Clyro's 'Many Of Horror (When We Collide)' - by host Dermot O'Leary, a moment that he described as "weird".
Asked to comment on Cardle's victory, winning judge Dannii Minogue stated: "Thank you, thank you for every single vote. This man deserves it, he won't let you down. It's been an incredible ten weeks."
Earlier, Minogue had given a heartfelt tribute to Cardle where she brought to light his prolonged struggles to make it in the music industry.
"[He's] a true, true gentleman. You can see how everybody speaks about you and you're a nice, nice guy.
"You have this incredible voice and I'm so glad we got to hear it on this shown, because I know you haven't had the belief in it and it's been a long, hard road to get here."
Cardle, who earlier performed Katy Perry's 'Firework' in tonight's show, gave a teary rendition of his debut single that was interrupted by a joyous reunion with the other X Factor finalists and particularly enthusiastic clinches from Aiden Grimshaw and third-place finishers One Direction.
After the performance, a smiling Cowell stated: "I've got to hand it to you Matt, you are one heck of a nice guy. You sang yourself to win this show."
Meanwhile, O'Leary commiserated runner-up Rebecca Ferguson and her mentor Cheryl Cole, but the Liverpudlian singer insisted that Cardle was a worthy winner.
"I'm so happy, so grateful and Matt's amazing," she said. "I'm just happy to have got this far."
Cardle's success hands Dannii Minogue her second win on the show, the first since she mentored Leon Jackson to victory in the 2007 series.
Cardle's winner's single, 'Many Of Horror (When We Collide)', which is expected to become this year's Christmas number one, will be available for download from midnight and in stores from tomorrow.