Kang received a Bachelor of Arts in English and Theater from Occidental College in Los Angeles, California, after which she had several short stories and poems published and also wrote a number of plays. She eventually returned to school, where she received a Master of Fine Arts degree in screenwriting from the University of Southern California. Her first job in the television industry came when she worked as an intern for the ABC medical drama series Grey's Anatomy and Private Practice.
Her first job as a staff writer was for the unaired NBC post-apocalyptic series Day One, which she got coming out of graduate school. Shortly thereafter, she was hired as a staff writer on the short-lived FX series Terriers, of which she wrote two episodes. In 2011, she joined the writing staff of the acclaimed horror drama series, The Walking Dead. In 2018, she became showrunner of The Walking Dead with its ninth season.