In November 2019, Kianni skipped school to join a group of protesters organized by Extinction Rebellion who intended to stage a week-long hunger strike and sit-in at the Washington, D.C., office of Speaker of the House Nancy Pelosi, demanding that she speak with them for an hour on camera about climate change.[6] Locally, there were roughly a dozen participants; at 17 years old, Kianni was the youngest, and one of two women.[2][7] Kianni was not a member of XR, and only participated in the first day of the sit-in, but gave a prepared speech and interviews to the press, and continued the hunger strike remotely.[2][8] Kianni wrote about her participation in the protest for Teen Vogue.[3] In February 2020, Kianni was named a spokesperson for Extinction Rebellion.[9][10]