Celebrity Parents Kim Kardashian Celebrates 'Baby Girl Twin' Chicago on Her 4th Birthday: 'The Ultimate Princess' "You really have brought so much joy into our family and I love you so so soooo much!!!!" Kim Kardashian wrote on Saturday By Nicholas Rice Nicholas Rice Instagram Twitter Nicholas Rice is an Associate Editor for PEOPLE Magazine. He began working with the brand as an Editorial Intern in early 2020, before later transitioning to a freelance role, and then staff positions soon after. Nicholas writes and edits anywhere between 7 to 9 stories per day on average for PEOPLE, spanning across each vertical the brand covers. Nicholas has previous work experience with Billboard, POPSUGAR, Bustle and Elite Daily. When not working, Nicholas can be found playing with his 5 dogs, listening to pop music or eating mozzarella sticks. People Editorial Guidelines Published on January 15, 2022 11:47 AM Share Tweet Pin Email Photo: Kim Kardashian/Instagram Happy birthday, Chicago West! On Saturday, the younger daughter of Kim Kardashian and Kanye West celebrated her fourth birthday, which her famous mom marked with a sweet tribute post on Instagram. "My birthday baby girl Chi Chi turns 4 today!" Kardashian, 41, wrote alongside various photographs and videos of her little one. "My independent baby girl twin." "You are the most lovable huggable snuggable baby girl on the planet. The ultimate princess!" she continued. "I can't wait to celebrate with all of the Barbies and LOL Dolls a girl could dream of lol." Kim Kardashian West Is Working on 'Being Stricter and Saying No' with Her Kids: 'I Usually Give In' Added the SKIMS founder: "You really have brought so much joy into our family and I love you so so soooo much!!!!" Kardashian also spent the day sharing throwback videos of Chicago with her siblings and cousins on Twitter. Chicago was born via surrogate at 12:47 a.m. on Jan. 15, 2018, weighing 7 lbs., 6 oz. "Kanye and I are happy to announce the arrival of our healthy, beautiful baby girl," Kardashian wrote in a post titled "She's Here!" at the time. Want to get the biggest stories from PEOPLE every weekday? Subscribe to our new podcast, PEOPLE Every Day, to get the essential celebrity, entertainment and human interest news stories Monday through Friday. "We are incredibly grateful to our surrogate who made our dreams come true with the greatest gift one could give and to our wonderful doctors and nurses for their special care," she added. RELATED VIDEO: Kim Kardashian Says She's 'Done' Having Kids as She Celebrates Sister Kylie Jenner's Pregnancy News Last month, Kardashian and Chicago took part in some mother-daughter bonding when the pair spent time at the Asian Art Museum in San Francisco. Sharing a pair of sweet snapshots of herself with Chicago on Instagram, the mother of four captioned a photo in front of a fluorescent, interactive piece of artwork: "Team Lab at the Asian Art Museum in San Francisco." Alongside Chicago, Kardashian and her estranged husband, 44, share daughter North, 8, and sons Saint, 6, and Psalm, 2½.