Mitchell was born in Long Island, to a bluesman and an artist. Her youth included poverty, homelessness and alcoholism. She was repeatedly caught creating graffiti; she stopped after being arrested for it. She moved to Washington with her father at age six, but after he died of an overdose, she ended up returning to New York. There, she was arrested several times and eventually absconded to Los Angeles rather than be placed in foster care at age fifteen. For a while, she considered Union Station her home before purchasing a Jeep Cherokee and living in it in a garage in East Los Angeles; in an interview, she stated that she lived out of her car and felt safe in doing so.
Mitchell moved from singing to rapping after her mother gave a negative review of her voice, and mentioned that the turning point for her was when she heard Big Pun's Capital Punishment.
After moving to Los Angeles, she booked her own tours in such countries as Germany and Romania, sleeping on floors and collecting money from fans. Her first EP, Clean Windows Dirty Floors, was produced by DJ Hoppa. Her first LP, Smile You Have Teeth, was never released. Prior to its intended release, Mitchell's manager sent her a contract demanding $30,000 from the LP's proceeds. She subsequently decided to abandon the album and start anew.
Mitchell met Skrillex after she was contacted by him on MySpace, commending her work and requesting that they work together. The first track, WEEKENDS!!! was the result of Skrillex asking her to rap into his laptop the lyrics she was working on. Their second collaboration, "Bangarang", happened after he called her while he was on tour and asked her to record 16 bars about the Lost Boys. She forgot to close the window before recording it, and thus birds are audible in the recording. Mitchell has also released a mixtape, C.U.L.T: Too Young to Die. After that she released another EP, Inhale.