"Grateful to know her, proud to call her mine, & thankful for the life we will have together x."
Last week multiple outlets reported Hadid had given birth to a baby girl after her father, multi-millionaire Mohamed Hadid, posted an adorable letter addressed to his "little grandchild" on Instagram.
In April this year, Hadid announced her pregnancy to her fans while chatting to Jimmy Fallon on his late talk show.
Since the news, the pair have been isolating together at Hadid's family's Pennsylvania farm.
After announcing the happy news, Hadid shared gorgeous pregnancy photos throughout her journey.
At first, she said during an Instagram Live that she was hesitant to share her pregnancy journey due to bigger problems in the world regarding the coronavirus pandemic and Black Lives Matter rallies.
"I have been taking a lot of pictures of my bump and sending them to my friends and family, and it's been really cute and exciting. I have been trying to document it because people are saying don't miss it," she said.
"Right now I just want to experience it and I write in my journal a lot and I just don't want to worry about waking up every day and look cute and post something," she continued.
"A lot of people are confused by why I am not sharing more but I am pregnant through a pandemic, obviously my pregnancy is not the most important thing going on in the world, that's in part why I didn't feel a need to share, apart from with my family and friends."
Hadid and Malik have been dating on and off since 2015.