STORY: The 39-year-old previously ran the failed blood-testing startup Theranos, a company once valued at $9 billion.
Holmes was escorted from a vehicle into a federal women's prison camp in Bryan, Texas on Tuesday afternoon.
She rose to fame after she claimed her firm's small machines were revolutionary. Holmes said they could run a range of tests with just a few drops of blood.
Theranos collapsed after a series of articles in the Wall Street Journal in 2015 questioned the technology.
Holmes - once the world's youngest female self-made billionaire - was subsequently convicted of fraud at trial in California last year. She was sentenced to 11 years and three months behind bars.