Nunnari was born in Cleveland, Ohio, and studied chemistry at the College of Wooster before obtaining a Ph.D. in pharmacology from Vanderbilt University, working with Lee Limbird.

As a postdoctoral fellow with Peter Walter at the University of California, San Francisco, Nunnari pioneered the use of green fluorescent protein to visualize mitochondria in budding yeast, helping to establish the field of mitochondrial dynamics.

Since obtaining an independent position at the University of California, Davis, Nunnari and colleagues have investigated the molecular mechanisms underlying mitochondrial fission and fusion and explored the structure and function of membrane contact sites that link mitochondria with other organelles.

Nunnari was named editor-in-chief of the Journal of Cell Biology in August 2015, becoming the first woman to serve in this position.

[7] In 2022, Nunnari became a founding principal investigator at Altos Labs, a company focused on cellular rejuvenation programming to restore cell health and resilience, with the goal of reversing disease to transform medicine.