In the photo, Jenner, 58, posed between Flajnik, 31, and her girlfriend, entrepreneur Liz Heinlein. She captioned the shot: "Date night with Ben and Liz."
Flajnik has continually denied rumors that he and Jenner, who is separated from husband Bruce Jenner after 22 years, are dating, after he was seen driving her Bentley, vacationing with her in Mexico, visiting his Sonoma, Calif., winery with her and attending the Kanye West concert with her and her daughter Kim Kardashian.
"Kris is a very, very dear friend of mine," he said. Flajnik told People in October. "We are not dating, we're just working on a couple of projects together, so that's why we've been seen a lot as of late."
Jenner has yet to speak out on the rumors but told "Entertainment Tonight" earlier this month that, though she was in no rush to date, she would be open to younger men.
"You find who you fall in love with in life," she said. "If they happen to be a certain age, they happen to be a certain age."