The reality TV show's cameras caught the lovers as they hit the red carpet at the grand opening of Kat's Wonderland Gallery, in West Hollywood, California, in early September.
Onlookers were stunned to see the tattooed-duo together just two months after the cheating biker's divorce from actress Sandra Bullock was finalised.
At the event, both were quizzed by reporters over whether Kat, 28, had met Jesse's children, and the red-haired seductress was asked if she had been "smiling non-stop" since meeting the 41-year-old bad boy.
"I'm always smiling man, but I think it's harder for me to frown," she replied.
Asked whether they had yet mentioned the 'love' word, she said, "I don't really hang out with anybody unless I'm in love."
The hit reality TV show's producers had ignored Kat's demands to slash the juicy material from the episode. According to TMZ.com, bosses felt they would be "sacrificing the integrity of the show" by ignoring Kat's headline-making relationship.