The leggy blonde, who is currently dating the show's renowned lothario Spencer Matthews, was filming alongside her new squeeze in Knightsbridge, London.
The pair were seen bumping into Louise Thompson, Spencer's ex. Stephanie, 27, was photographed looking on as Spencer gave his former girlfriend a big hug.
Spencer and Stephanie have been dating for several weeks. Rumours of a romance were first sparked when the pair attended an event together in London back in June.
The relationship was then confirmed with a series of photographs of the pair together on Twitter last month.
"Miss the Pratt... @stephaniepratt," Spencer wrote alongside a black and white picture of the pair posing together.
Stephanie replied with a photo of the pair kissing. "Miss u too babe @SpencerGeorgeM," she captioned the snap.
Spencer's most recent ex is Lucy Watson, who dumped the 25-year-old after learning of his infidelity on Twitter.
Speaking about his new romance with the US star, Lucy told new! magazine, "They're obviously quite fame-hungry and desperate for attention.
"Normally I cut exes out of my life so I don't know what they're up to, but with Spencer it's difficult because he's trying to be pictured as much as possible with Stephanie."
Before Lucy, Spencer and Louise dated for more a year until she discovered that he had cheated on her.
The sixth series of Made in Chelsea will return to E4 later this year.