Angry Little Girls was developed from Kim, the "Angry Little Asian Girl", a character she developed in 1994 when she was a sophomore at UC Berkeley. She developed the character after attending Spike and Mike's Sick and Twisted Festival of Animation with a friend. That same night after getting home from the animation festival, Lee stayed up drawing with typing paper and crayola markers and made the first episode "Angry Little Asian Girl, the First Day of School." Three years after initially creating the first episode of the Angry Little Asian Girl, she created four more, and sent the five episodes titled Angry Little Asian Girl, Five Angry Episodes to festivals where they were well-reviewed by critics of the LA Times and LA Weekly. Audience members came up to her after screenings saying that ALAG spoke for them and that they too had similar experiences growing up in America. She realized she had hit a nerve. She had the idea to make a batch of T-shirts. She quickly sold out by word of mouth, prompting her to launch a shop on the website www.angrylittleasiangirl.com in late 1997. She packed the shirts herself and mailed the orders every morning from the neighborhood post office. She also kept shirts in the back of her station wagon with a cash box and a card table and sold shirts wherever she could. The shirts sold out many times over.

She is also a film and television Actress, with roles in the 1998 film Yellow and the 2002 film Better Luck Tomorrow. She was a series regular in the short-lived Sci Fi Channel series Tremors, and had a recurring guest role on NBC's Scrubs. Lee made a guest appearance in the first episode of Season Four of HBO's Curb Your Enthusiasm, ironically playing an angry Asian woman, who launches a physical and Verbal attack on star Larry David after he suggests Tang is a Common Chinese name. Lee was also in the episode "Animal Pragmatism" of Charmed as Tessa, a college student.

This experience of taking the shirts out on the road proved to be invaluable. Lee met many people, particularly women of all ages and ethnicities who responded to the anger that ALAG unleashed. She observed how women did not feel that they were allowed to be angry, but somehow, her character let them tap into their own anger in a funny and "harmless" way. During this time, people kept referring to the video as a "comic strip." Instead of correcting them, she took it as a suggestion and decided to expand ALAG to include other girls of different backgrounds and personalities. She took 2 years to teach herself how to draw comics with books checked out from the library. With the newly created characters, and an umbrella name of "Angry Little Girls" which included other girls; Deborah the disenchanted Princess, Maria the crazy little Latina, Wanda the fresh little soul sistah, and Xyla the gloomy girl, Lee turned it into a weekly comic strip self-published on her website www.angrylittlegirls.com. She also began submitting her comic strips to syndicates in hopes of getting syndicated in newspapers. But after numerous rejection letters and realizing her work would never fit in the mainstream, she decided to buck the system and draw whatever she was inspired to. After finding her true voice, a publishing deal came quickly thereafter. In 2005, the first book of collected Angry Little Girls strips was published by Harry N. Abrams. By 2007, Angry Little Girls merchandise, especially tote bags and wallets were popular selling items in malls across the US. Lee has 6 Angry Little Girls books published as well as numerous merchandise licensees. 2014 marks the 20-year anniversary of ALAG's creation. Also in December 2014, Angry Little Asian Girl had a short run on a cable network and is now a web series.