Kiko Mizuhara started her modeling career at the age of twelve when she entered an audition contest for Seventeen magazine in which readers selected their favorite new face for the publication.

[12] She is the oldest of the two daughters of Song Pal-choong (better known by her Japanese alias Yae Toyama, née Mizuhara),[12] a Zainichi Korean from Nagasaki, Japan, and Todd Mason Daniel,[12] an American from Texas.

[20] Mizuhara was chosen to open and close the Fall/Winter 2014 Show of Sretsis, a Thai-brand clothing line, during the Mercedes-Benz Fashion Week in Tokyo.

Mizuhara has also shot ad campaigns for Diesel, Phillip Lim, Vivienne Tam, Reebok, Kitsuné, Tiffany & Co., Shiseido, etc.

[24][25] She played a supporting role in Mika Ninagawa's Helter Skelter (2012), which is based on the award-winning manga of the same name by Kyoko Okazaki.

[30] In 2014, she starred in the drama Shitsuren Chocolatier and played as a witch doctor in Trick The Movie: Last Stage,[31] filmed in Kuching, Malaysia, where she spoke Bahasa.

In 2015, she was part of the main cast of the Japanese drama Kokoro ga Pokitto ne (Crazy For Me) and portrayed Mikasa Ackerman in the live action adaptation of Attack on Titan.

Mizuhara has also produced a collection of headgear that blends Harajuku style with '90s streetwear in collaboration with Opening Ceremony Japan and Harlem-based label Gypsy Sport.

[citation needed] Other celebrities who have worn her items from this collection include Brown Eyed Girls members Ga-In and Sunmi.

In 2018, Office Kiko announced a new line of boots and shoes in collaboration with the Esperanza, a Japanese footwear company catering to young women.

[citation needed] Mizuhara stated in an interview with NBC News that she has previously dated women, something that influenced her portrayal of Rei in Ride or Die.