Garrett, who became president of the Ivy League school July 1, died Sunday night at her home, Cornell said.
A legal scholar, Garrett came to USC's law school from University of Chicago Law School in 2003 and was appointed USC provost in 2010. Her departure to become Cornell's first woman president was announced four years later. She died after only a few months on the job.
Upon leaving USC, she had told a reporter that, as a former undergraduate at the University of Oklahoma, she never imagined she would head an Ivy League school. "It feels great," she said.
Garrett attended the University of Virginia School of Law and clerked for Supreme Court Justice Thurgood Marshall before rising through university administrative ranks in Chicago and L.A. on her way to Ithaca. She also served on the California Fair Political Practices Commission from 2009 to 2013.
"While Beth's tenure as president has tragically been cut short, her efforts over the last eight months have set the university on a path toward continued excellence," said Robert Harrison, chairman of the Cornell board of trustees. "She will leave a lasting legacy on our beloved institution and will be terribly missed."
Cornell, in central New York, planned a moment of silence Monday afternoon and a memorial service at a later date.
Garrett described herself as a fan of hiking, needlepoint and mystery novels. Her husband, Andrei Marmor, teaches at Cornell's law school.