The Hills and The City star, who runs the Whitney Eve fashion line, will be joined by another new judge, male model Tyson Beckford, The Mirror reports.
The pair replace stylist Grace Woodward and model Charley Speed and will judge alongside supermodel Elle Macpherson and designer Julien Macdonald when the eighth series of the Sky Living show returns this summer.
"I am so excited to be joining Britain & Ireland's Next Top Model. I'm a huge fan of the show and am honoured to be in the company of the talented fellow judges and host, all fashion figures and designers I admire," Port said of her new role.
"As a designer and someone who loves fashion, this is a role I'm really looking forward to. Plus any chance to spend more time in the UK is an added bonus."
Beckford added: "Having guest judged on last season's series, it's fantastic to be taking on a permanent role on the panel this year and I'm looking forward to finding the next editorial star."
Macpherson, who also executive produces Britain & Ireland's Next Top Model, said it was "incredibly important" to have judges like Port and Beckford who can bring "personal experience and success" to the show.
Beckford previously hosted Make Me A Supermodel.
It had been rumoured that Kelly Osbourne would be asked to judge Britain & Ireland's Next Top Model in 2012 to "shake things up".