A jury convicted Holmes in January on four counts of wire fraud and conspiracy. Each count carries a maximum 20-year prison term. Any sentence would likely be served concurrently.
Prosecutors said Holmes lied to investors from 2010 to 2015 by promising Theranos' technology could run many tests on one drop of blood from a finger prick.
On Monday, Davila rejected Holmes' requests for a new trial, including over a claim that a key prosecution witness visited her at home and made statements that undermined his testimony.
Holmes founded Theranos in 2003 at age 19, before dropping out of Stanford University. Theranos was once valued at $9 billion, and Forbes magazine in 2015 estimated Holmes' net worth at $4.5 billion.
More than 130 friends, family, investors and former Theranos employees submitted letters to Davila urging leniency for Holmes.
Her partner Billy Evans called Holmes, known as Liz, "honest, humble, selfless, and kind beyond what most people have ever experienced."
Theranos' former president Ramesh "Sunny" Balwani was convicted in July of defrauding investors and patients about the company. His sentencing is scheduled for Dec. 7.
