Following in mum's footsteps, the two youngsters have taken a starring role to help Katie launch her new collection of childrenswear, showcasing a number of outfits in photographs posted on her KP Equestrian website.
Judging by the results, Junior, four, and his two-year-old sister had a ball taking part – the little boy in particular striking some poses worthy of his model mother.
And Princess is a natural too, standing with her hands on her hips in one picture, wearing an 'I heart horses' T-shirt, described by 31-year-old Katie as a "summer must-have".
Speaking to the Daily Mail, Alex Reid's new wife said of the Spring/Summer 2010 range: "I can't believe this is the fourth collection for KP Equestrian. How time flies!"
"One of my favourite pieces is the narrow-striped hoodie; the bubble-gum pink velour is just amazing, and I reckon the I Love Horses tee is a summer must-have!"
It is not known what her ex-husband Peter Andre makes of his children's modelling debut.
Meanwhile, it has been reported that Katie might be taking a leaf out of Lily Allen's book and making a cameo appearance on hit Australian soap, Neighbours.
With her show, What Katie Did Next, being well received Down Under, the Brighton-born business woman is flying to Oz in the summer to film the next run of the reality series and launch her horse riding range.
"The guys on Ramsay Street are keen to get her on for a one-off," a source told the Daily Mirror. "Who knows, Katie and Alex could be the next Kylie and Jason."