Posting a sweet pic of her son's tiny fingers holding onto hers, Hilton captioned the pic, "You are already loved beyond words 💙"
A source tells ET, "Paris Hilton and Carter Reum welcomed a baby boy via surrogate. Paris is so incredibly happy and has always dreamed of being a mom. Her friends and family are thrilled for her and know she is going to be the best mom."
Many of those friends hopped into the comments section of her post to share the love. Kim Kardashian, Hilton's pal and former stylist, commented, "So happy for you guys!!!"
Hilton replied, "@kimkardashian thank you love! 💞So in love with my lil angel."
Lindsay Lohan, who recently reconnected with Hilton after years of estrangement, wrote, "Congratulations!!! ❤️🙏❤️"
Supermodels Heidi Klum and Naomi Campbell also commented, with Klum writing, "I am Sooooooo happy for you . Sending lots and lots of love ❤️" and Campbell commenting, "Congratulations to you both , biggest blessing 💙"
Garcelle Beauvais -- who co-stars on The Real Housewives of Beverly Hills with Paris' mom, Kathy Hilton, and her aunt, Kyle Richards -- wrote, "So happy for you and Carter, what a lucky baby💙"
Paris' pal, Ashley Benson, commented, "Love you," to which the new mom replied, "Love you too sis 🤗"
Nicky Hilton, Paris' sister, also shared a sweet post following the baby news. "Welcome to mommyhood @ParisHilton! 👶🍼🧸 So so incredibly happy for youuu! 🥰 It’s the most beautiful ride. There is no greater love. You are going to be the best mommy. What a lucky boy! 💙," she captioned a throwback photo of her and Paris with their mother, Kathy.
Paris has been very open about wanting to start a family with her husband. During an April 2022 appearance on The Bellas podcast, she shared, “We've been talking about kids since the beginning -- since the first couple months of dating. We would love to have twins, that would be amazing. We want like three or four."
The surprise baby announcement comes just a couple of months after Paris revealed she was undergoing IVF treatments. "IVF is always a journey for everything but we're so fortunate that we have lots of healthy embryos ready and waiting to be part of our Cutesy Crew!" Paris explained in November 2022. "As everyone knows I have an extremely busy work and travel schedule but nothing gets me more excited than becoming a mom in 2023!"