She was born and raised in Richmond, Virginia to Korean parents. She is a Korean-American. She graduated from Maggie L. Walker Governor’s School for Government and International Studies in 1998. She attended the University of North Carolina at Chapel Hill, and later earned her Master of Fine Arts in creative writing at The New School, from which she graduated in 2006. Han resides in Brooklyn, New York City.

In 2014, Han released a young adult romance novel, To All the Boys I’ve Loved Before, about Lara Jean Song Covey, a high school student whose life turns upside down when the letters she wrote to her five past crushes are sent out without her knowledge. The novel was optioned for a screen adaptation in the weeks following its debut. The sequel, P.S. I Still Love You, was released the following year, and won the Young Adult 2015–2016 Asian/Pacific American Award for Literature. A third novel, Always and Forever, Lara Jean, was released two years later. The film adaptation of the first novel, starring Lana Condor in the lead role, began filming in July 2017 and was released by Netflix in August 2018, to positive reviews. She had a brief cameo in the film.