"We are cooperating with investigators and take those probes seriously", a Facebook spokesman told the Times in a statement.
The Times' report was released on Wednesday evening, while Facebook was dealing with a major outage.
It wasn't immediately clear what the grand jury was focused on or when its investigation began.
The criminal investigation adds to a laundry list of probes since the Cambridge Analytica revelations one year ago placed a spotlight on the company's data and privacy practices. The companies are just two of more than 150 tech firms that entered data-sharing deals with Facebook, which allowed the company sweeping access to hundreds of millions of Facebook users' personal information, including private Facebook messages. Apple, for example, was able to slurp up contact numbers and calendar entries from users who thought they'd disabled all sharing, unbeknownst to the users - though Apple maintains it had no idea Facebook had given it special access and that it removed no data from users' devices.
Facebook has defended the deals.
Trump to seek another $8.6 billion for border wall
"We hope he learned his lesson", the duo continued, adding that the money should be spent on education and workforce development. We have to be much tougher and have more constructive immigration policy , which we will be developing over a period of time.
The US Justice Department's fraud unit is also investigating the Cambridge Analytica scandal.
The deals sparked outrage - and have come under sharp scrutiny - since they were revealed in a investigation by the Times previous year.
Facebook is facing a slew of lawsuits and regulatory inquiries over its privacy practices, including ongoing investigations by the U.S. Federal Trade Commission, the Securities and Exchange Commission and two state agencies in NY.
Facebook gave companies including Netflix, Spotify, Microsoft, Sony and Amazon the ability to access user data long after it had stopped sharing data with most third-parties, the Times revealed.