After hosting the show at Wembley Arena, O'Leary admitted that he had suffered from nerves during rehearsals, but claimed that the stress and pressure had all been worthwhile.
"I loved it. One of my favourite finals that I've ever done," O'Leary told The Xtra Factor. "I did get nervous in the dress rehearsal... it's Wembley! You try to think of it as a bigger studio, but then you look up and there's 10,000 people. But the moment it started, we loved it."
O'Leary singled out Gary Barlow and Marcus Collins's duet on Billy Joel's 'Always A Woman' as a personal highlight, describing it as "very touching" and "the first stop and breathe moment".
He added: "What I love is that the final is so celebratory. The judges acknowleged that as well."
The X Factor final concludes on Sunday (December 11) at 7.30pm on ITV1.
> X Factor final: Live Blog
> Amelia Lily eliminated from X Factor final