The One Direction hunk stopped by the supermodel and her husband Rande Gerber's abode in Malibu, California, to make ham and pineapple pizzas with her son Presley, 14, and 11-year-old daughter Kaia, but his secret stay was revealed when Presley posted a picture of their cooking session on Instagram.
In a message accompanying the image, he wrote: "Thanks for stopping by the house again and helping the boys and I make our pizzas @harrystyles (sic)"
Harry was quick to respond to the teenager and promised to take Cindy's kids surfing next time he was in the area.
He wrote: "Anytime brother.. See you for surfing soon. (sic)"
Presley replied: "Looking forward to it @harrystyles (sic)"
It's not the first time the 19-year-old star has visited Cindy's house to see her children after popping over last month to see Presley after he had his tonsils out.
He wrote on Instagram: "I was chilling at my house after I got my tonsils taken out and my sister had a friend over to hang.
"This guy knows how I feel."
Last year, Harry and his One Direction bandmates - Niall Horan, Louis Tomlinson, Zayn Malik and Liam Payne - visited Johnny Depp's home recording studio to perform for the actor's 13-year-old daughter Lily-Rose.