Hailey Bieber, Selena Gomez, and Rihanna Use This 4-Minute Treatment for Smooth, Healthy Hair

What do Hailey Bieber, Rihanna, and Selena Gomez have in common? In addition to revolutionizing beauty brands, and impeccable style, they also seem to never have bad hair days. And it turns out they share the same salon-grade secret to keeping their hair healthy and damage free: The K18 Leave-In Molecular Repair Hair Mask (Buy It, $75, sephora.com).

"My favorite hair product right now is called K18," Bieber noted to Refinery29 back in 2021; since then, she's used the mask to protect her hair throughout the many color changes she's tried out this year, according to the brand. "It's so good, I use that all over my hair every time I get out of the shower," the supermodel added. Back in September, Rihanna's stylist Yusef Williams told Allure that the singer-turned-beauty-mogul prepped her mane for the Met Gala with the K18 hair mask, explaining that he included the extra step to "keep Rihanna's hair strong and healthy over time." And as far as he could tell, it had "really been working."

What's more, in an interview with InStyle earlier this year, Gomez noted that incorporating the hair mask into her morning beauty routine made her feel like "a grown woman." And with a mere 4-minute leave-in time, this easy-to-use treatment makes adulting truly hassle-free. (Psst: Selena Gomez is actually the queen of beauty secrets. Check out her $5 skincare find.)

Buy It: K18 Leave-In Molecular Repair Hair Mask, $75, sephora.com

With a blend of frizz-reducing behentrimonium chloride and strengthening wheat protein, this hard-working mask restores body, length, and softness to hair, even when it's damaged by bleach, dye, chemicals, heat, or a combo of all four. But the true star of the formula is the brand's patented K18 peptides, which are small enough to fill and mend cracks in broken keratin bonds (i.e. a key protein in hair). After thoroughly towel-or air-drying hair, apply one pump of the mask evenly from the root to tip of it. The formula jumps into action immediately, reducing the normal wait time associated with leave-in treatments — 10 minutes to several hours —to just four minutes. And while all this seems too good to be true, customers swear the K18 product is legit.

One shopper with bleach-treated strands said that after just three uses, they felt a difference in texture. The high praise continued as they deemed the mask "better than Olaplex." Another user noted that the treatment made their "otherwise frizzy, straw-ended hair" feel so soft and smooth after just three applications. And some reviewers saw results even faster; a third person's hair transformed from "dry, frizzy, color-treated, [and] damaged," into "soft, smooth, beautiful, vibrant" in just one use. (Want more recs for damaged hair? Shoppers say this Olaplex dupe is better than the original.)

With the ability to work on all hair types, from coily to super fine, this no-stress hair mask is exactly what the beauty industry (and any beauty lover) needs. Plus, it's easier to find than ever after launching at Sephora earlier this year. Shop the Gomez and Rihanna-approved pick at Sephora.com before it flies off the shelves.