Donato served as a law clerk for Judge Procter Ralph Hug Jr. of the United States Court of Appeals for the Ninth Circuit from 1988 to 1989.

From 2009 to 2014 he served as a litigation partner in the San Francisco office of Shearman & Sterling LLP.

On February 12, 2014, Senate Majority Leader Harry Reid filed for cloture on Donato's nomination.

Donato emphasized that he was the fifth federal judge to find that Wolf's appointment was unlawful and criticized the government for recycling the same arguments it had used to unsuccessfully defend Wolf's appointment in the past, writing: "In effect, the government keeps crashing the same car into a gate, hoping that someday it might break through.

[13] The United States Court of Appeals for the Federal Circuit upheld Donato's ruling in a 2-1 decision.

The rule allocated funds based on a school's total enrollment, rather than on the number of low-income students.

[16][17] Donato blocked the Department of Education and Secretary Betsy DeVos from enforcing this rule, saying their arguments in favor of it were a form of "'interpretive jiggery-pokery' in the extreme" (quoting Justice Antonin Scalia's dissent in King v.

[15][18] In February 2021, Donato approved a $650 million settlement between Facebook and a class of plaintiffs suing under the Illinois Biometric Information Privacy Act.