Kianni became interested in climate activism while in middle school in Tehran, when one night the stars were obscured by smog, and it "was a signal that our world is heating up at a terrifying pace".[1] She later joined Greta Thunberg's group, Fridays for Future, and would take time off from class to support action on climate change.[3] She helped organize the 2019 Black Friday climate strike.[4] By 2019 she was a national strategist for Fridays for Future, and a national partnerships coordinator for Zero Hour, another environmental advocacy group.[3][4]