She was speaking as the tenth run of the ITV series was launched in London.
The former Pussycat Dolls singer, who is mentoring the girls' category, said: "Having Mrs O back on the panel brings a whole new energy and brings something out in each of the judges.
"I just feel the confidence. She brings out the feisty in me,"
Sharon Osbourne said it was "wonderful" to return to the show.
The 60 year-old, who left the ITV talent competition in 2008 amidst reports that there was tension with fellow judge Dannii Minogue, has joined Scherzinger along with Gary Barlow, and Louis Walsh on the judging panel for the upcoming season, replacing Tulisa Contostavlos.
On the red carpet at London's Mayfair Hotel she said: "It's wonderful, it feels absolutely wonderful to be back. The show is so much fun, it really is.
"I kind of left under a cloud last time around and it wasn't really professional of me. I left two weeks before the show was due to start.
"It wasn't the right thing to do. So this sort of makes it alright. It's gone full cycle and it ends on a high note."
Osbourne - who will mentor the over-25s group - revealed she is responsible for bringing "laughter and fun" to the panel.
The show, which will be hosted by Dermot O'Leary, with Caroline Flack and Matt Richardson on spin-off show The Xtra Factor, returns on August 31.