Carolyn Ruth Bertozzi (born October 10, 1966) is an American chemist and Nobel laureate, known for her wide-ranging work spanning both chemistry and biology. She coined the term "bioorthogonal chemistry" for chemical reactions compatible with living systems. Her recent efforts include synthesis of chemical tools to study cell surface sugars called glycans and how they affect diseases such as cancer, inflammation, and viral infections like COVID-19. At Stanford University, she holds the Anne T. and Robert M. Bass Professorship in the School of Humanities and Sciences. Bertozzi is also an Investigator at the Howard Hughes Medical Institute (HHMI) and is the former Director of the Molecular Foundry, a nanoscience research center at Lawrence Berkeley National Laboratory.

She received the MacArthur "genius" award at age 33. In 2010, she was the first woman to receive the prestigious Lemelson-MIT Prize faculty award. She is a member of the National Academy of Sciences (2005), the Institute of Medicine (2011), and the National Academy of Inventors (2013). In 2014, it was announced that Bertozzi would lead ACS Central Science, the American Chemical Society's first peer-reviewed open access journal, which offers all content free to the public. Since 2021 she has been a member of the Accademia dei Lincei. As an open lesbian in academia and science, Bertozzi has been a role model for students and colleagues.

Bertozzi was awarded the 2022 Nobel Prize in Chemistry, jointly with Morten P. Meldal and Karl Barry Sharpless, "for the development of click chemistry and bioorthogonal chemistry".