"I'm just thinking a lot about Jack today," she captioned the post. "Our house is very open about life, death, grief, everything really."
The 34-year-old shared two videos to Instagram to capture the 'beautiful' moment, praising Luna for her empathy.
"We try to explain things well and answer every question imaginable in a beautiful, spiritual but literal way," the 34-year-old continued.
"I know this is a weird post but I just wanted to share these to always remember my incredibly empathetic little mini. Life is infinitely better with her in it."
"I miss u, Jack. we miss you a lot," she concluded the post.
im just thinking a lot about jack today. our house is very open about life, death, grief, everything really. we try to explain things well and answer every question imaginable in a beautiful, spiritual but literal way. I know this is a weird post but I just wanted to share these to always remember my incredibly empathetic little mini. life is infinitely better with her in it. I miss u, jack. we miss you a lot.
In the first video, the model explains that they just got baby Jack's ashes back, and she came downstairs to fund that Luna had paid a visit, leaving him her teddy and her favourite snack.
"This is the cutest most beautiful thing I have ever seen," the mum-of-two gushed. "She's amazing."
The second video shows Luna sitting with the teddy bear next to Jack's ashes as she chats away.
"Hi guys, this is Jack and Teddy. I'm Luna," the four-year-old says in the video. "How are you doing today?"
Teigen lost her son just over a month ago at 20 weeks, after she was diagnosed with partial placenta abruption, which occurs when the placenta separates from the inner wall of the uterus before birth and causes heavy bleeding.
The 'Cravings' author recently revealed she had their baby's name, Jack, tattooed onto her right wrist, sitting just above her other tattoos which say "John — Luna — Miles."
Teigen penned an emotional essay for Medium in October, detailing her devastating loss, explaining to her social media followers that she wrote it hoping it would help her find closure.
We are shocked and in the kind of deep pain you only hear about, the kind of pain we’ve never felt before. We were never able to stop the bleeding and give our baby the fluids he needed, despite bags and bags of blood transfusions. It just wasn’t enough. . . We never decide on our babies’ names until the last possible moment after they’re born, just before we leave the hospital. But we, for some reason, had started to call this little guy in my belly Jack. So he will always be Jack to us. Jack worked so hard to be a part of our little family, and he will be, forever. . . To our Jack - I’m so sorry that the first few moments of your life were met with so many complications, that we couldn’t give you the home you needed to survive. We will always love you. . . Thank you to everyone who has been sending us positive energy, thoughts and prayers. We feel all of your love and truly appreciate you. . . We are so grateful for the life we have, for our wonderful babies Luna and Miles, for all the amazing things we’ve been able to experience. But everyday can’t be full of sunshine. On this darkest of days, we will grieve, we will cry our eyes out. But we will hug and love each other harder and get through it.
"I didn't know how to come back to real life so I wrote this piece for Medium with hopes that I can somehow move on but as soon as I posted it, tears flew out because it felt so....final," she said.
"I don't want to ever not remember Jack."
Social media users thanked Teigen for sharing the post, and being so open about how she is dealing with the tragic loss.
"Holding space for your grief. Thank you for inviting us into this sacred time," one user wrote. "You are so brave and so loved."
"Your family has helped so many people that have lost a child in silence," agreed another.