Omar Mwannes Yaghi (ওমর ইয়াগি) is a Jordanian-American chemist known for pioneering reticular chemistry and for the development of metal–organic frameworks (MOFs). He was awarded the 2025 Nobel Prize in Chemistry, shared with Richard Robson and Susumu Kitagawa, for this work. Yaghi is a University Professor and James and Neeltje Tretter Endowed Chair in Chemistry at the University of California, Berkeley. He is also an affiliate scientist at Lawrence Berkeley National Laboratory, founding director of the Berkeley Global Science Institute, and a member of the U.S. National Academy of Sciences and the German National Academy of Sciences Leopoldina. In January 2025, he became the seventh president of the World Cultural Council, an international organization promoting cultural and scientific advancement.

Omar Mwannes Yaghi was born in Amman on February 9, 1965, to a Palestinian refugee family that had fled from the Gaza Strip during the 1948 Palestinian expulsion and flight. He grew up in a crowded household with many children, all living in a single room that also housed the family's livestock. The family had limited access to clean water and no electricity.

At the age of 15, encouraged by his father, he moved to the United States. Although he knew little English, he began classes at Hudson Valley Community College and later transferred to the State University of New York at Albany, where he completed his undergraduate degree. He pursued his graduate studies at the University of Illinois at Urbana–Champaign, earning his PhD in 1990 under the guidance of Walter G. Klemperer. He then served as a National Science Foundation postdoctoral fellow at Harvard University (1990–1992) under Richard H. Holm.

Yaghi began his academic career as an assistant professor at Arizona State University (1992–1998). He then held the Robert W. Parry Professorship of Chemistry at the University of Michigan (1999–2006), followed by the Christopher S. Foote Professorship of Chemistry and the Irving and Jean Stone Chair in Physical Sciences at the University of California, Los Angeles (2007–2012).

In 2012, he moved to the University of California, Berkeley, where he is the James and Neeltje Tretter Professor of Chemistry. From 2012 to 2013, he served as the director of the Molecular Foundry at the Lawrence Berkeley National Laboratory. He is the Founding Director of the Berkeley Global Science Institute and a co-director of the Kavli Energy NanoSciences Institute, a partnership between UC Berkeley and the Lawrence Berkeley National Laboratory. He also co-directs the California Research Alliance by BASF and the Bakar Institute of Digital Materials for the Planet.

In 2020, Yaghi founded Atoco, a California-based startup focused on commercializing his advancements in MOF and COF technologies for carbon capture and atmospheric water harvesting.

In 2021, he co-founded a second startup, H2MOF, which applies his discoveries in reticular chemistry to address challenges in hydrogen storage.