The Fashion Police co-host confirmed on Wednesday night (8 January) that she and the vegan chef had called time on their relationship after two years together.
A rep for Kelly described the split as "amicable" and said the former couple "continue to have nothing but the utmost respect for one another."
Her spokesperson added to People: "Kelly is looking forward to a new year full of fresh beginnings."
The broken engagement comes just a month after the pair were seen looking happy together on the red carpet at a charity gala in Los Angeles.
Kelly revealed her engagement in July last year, surprising us all by saying Matthew had popped the question the previous year but they'd kept it a secret.
In July 2013 she told her mum Sharon's TV show The Talk: "People know we got engaged in December of last year, but kept it a secret for six months. I realised very quickly that in Hollywood people don't realise that you get married for love, they think you get married for attention and I don't want to do a reality show. I've already done that."
After confirming her engagement via Twitter that month, the star had said: "Thank you so much to everyone for congratulating Matthew & I! We are the happiest couple on earth right now! Xoxo."
She has yet to address the break up on Twitter, although did post a cryptic tweet overnight, suggesting she was looking at the situation in a positive light.
"It's all about perception sometimes the bad things that happen in life aren't really bad at all especially when you learn something from it!"