The Guest In Residence founder layered a cardigan over a plunging v-neck vest and added black trousers.
She added a final covering of a leather blazer coat and stepped out in a pair of pointy-toe leather shoes.
For her part, Yolanda donned cropped black slacks and wore a gray jacket covered with black lace.
The younger Hadid pulled her blonde hair back into a neat bun and she wore sepia-tinted aviators.
She was adorned in jewelry that included layered gold necklaces and small earrings.
The designer and mother-of-one carried a small black leather handbag as she headed to a waiting car.
Despite the sad occasion, the beauty smiled at fans and gestured with a thumbs-up.
Yolanda wore black leather stiletto boots with a pointed toe and she also wore aviator-style spectacles.
Her frosty blonde locks were arranged in a sleek, spiky top knot bun and she wore a light face of makeup.
The former agency president passed away at the end of October following an unspecified, short illness.
He was 60-years-old and had stepped down from his role at IMG in March of this year.
Gigi was among the first celebrities to mourn Bart with a thoughtful social media tribute.
Taking to Instagram after hearing the news, she reposted the death announcement posted on his official account.
Hadid wrote, ‘Ivan. I don’t yet have words for this loss. I will never forget your spirit and hugs, your support and fight for others. Thank you, thank you, thank you.. for everything.’
At the end of the message, she added: ‘Rest In Peace Legend. Mr. Bart, Forever “My Boss.” You are so loved.’