Yassamin Ansari (/ˈjɑːsəmɪn ɑːnˈsɑːri/ YAH-sə-min ahn-SAH-ree, born April 7, 1992) is an American politician and climate policy activist who has served as the U.S. representative for Arizona's 3rd congressional district since 2025. A member of the Democratic Party, she previously served on the Phoenix City Council from 2021 to 2024.

At the time of her election to the Phoenix City Council, Ansari was the youngest person to be elected to the council and the first Iranian American elected to public office in Arizona. In 2024, she was elected to the House to succeed Ruben Gallego, who was elected in the 2024 Senate election. Ansari is also the youngest female member of Congress.

Ansari was born in Seattle, Washington, to parents who immigrated to the United States from Iran. Ansari grew up in Scottsdale, Arizona and attended Chaparral High School. In high school, she organized with the Arizona Democratic Party in support of Barack Obama's 2008 presidential campaign and worked with her mother to tutor Somali refugees. Ansari attended Stanford University, and received a bachelor's degree in international relations. During college, Ansari interned for Nancy Pelosi.

After graduation, she was selected for The John Gardner Fellowship Program and started working in the office of UN Secretary-General Ban Ki-moon. She worked as a senior policy advisor with Ban, spending a year working on the Paris Agreement, and later worked in the same role with Ban's successor, António Guterres. She started working towards a master's degree in international relations and politics from St. John's College, Cambridge in 2016 as a Gates Cambridge Scholar, which she ultimately received. She continued to be involved in promoting climate action, helping plan the Climate Action 2016 Summit, the Global Climate Action Summit, and the first U.N. Youth Climate Summit.

Ansari ran in a November 2020 election to fill the seat vacated by Michael Nowakowski, representing Phoenix's 7th District. The top two of the five contenders in the general election, Ansari and Cinthia Estela, continued to a runoff election that took place on March 9, 2021. Ansari took office as a council member on April 19, 2021.

While in office, she created an Office of Heat Response and Mitigation. It has sought to plant trees, reduce pavement heat absorption, educate residents, and distribute resources including water. She helped develop a plan to promote use of electric vehicles, and advocated for the city to purchase hydrogen fuel cell and battery electric public buses. She attended the 2021 United Nations Climate Change Conference with Phoenix mayor Kate Gallego, as well as the 2022 United Nations Climate Change Conference.

Along with other Phoenix City Council members, Ansari was criticized in 2022 for using a suite at Footprint Center, a sports venue owned by the city, to watch games and concerts; following the criticism, the council voted to review its economic development efforts and consider leasing out the suite.

Ansari resigned her City Council seat on March 28, 2024, to focus on her congressional campaign. Former Hayden Mayor Carlos Galindo-Elvira was appointed to fill the remainder of her term.