The "Underworld" star shared some slightly awkward intel about both her mother and daughter, Lily Mo Sheen, during her appearance. First up was mum, who got the spotlight after Kimmel asked whether Beckinsale had ever heard of Reddit before.
"I know Reddit is the one where sometimes you can find pictures of porn stars with your own face on it, isn't it?" she asked. "I've been sent a few, quite distressing photos of myself very busy actually. Not just in a wicker chair naked, but involved with more than one person. So when I got sent it, I just immediately sent it to my mother with no explanation."
Her mom's reaction: "She's used to shocks but, really offensively, I get a text back, 'Oh dear! Oh no! Oh phew, you've got hardwood floors and that's a carpet!'"
"She was like, what can I possibly cling onto that proves my case," Kate continued. "Not my six African American boyfriends all at once, but the fact that that's a carpet!"
Earlier in the show, she also put her daughter -- who was shown sitting in the studio audience -- on the spot by telling Kimmel the 18-year-old beauty has a crush on him.
Watch the awkwardness ensue around the 1:25 mark above.