The couple revealed on Sunday that they welcomed their second baby together, who was born on Saturday.
"We are so excited to announce the birth of our second daughter, Eloise Christina Schwarzenegger Pratt. We feel beyond blessed and grateful," they wrote in separate Instagram posts.
A source told PEOPLE in December that Chris and Katherine are "ecstatic" about welcoming baby No. 2 to their family. "They always hoped for Lyla to have another sibling. They feel very blessed," the insider said.
The source said that Katherine "loves being a mom," adding: "Lyla is her world. She has help, but is also very hands-on."
VALERIE MACON/AFP via Getty Katherine Schwarzenegger Pratt and Chris Pratt
"I've always wanted to be a mom and I have always really looked forward to this time in my life and been really excited about it," she shared. "And I feel really just so blessed to be able to experience it and also experience it with my husband, and she's just the best."