"I believe that PrivateCore's technology and expertise will help support Facebook's mission to help make the world more open and connected, in a secure and trusted way," Facebook's Joe Sullivan said.
"Over time, we plan to deploy PrivateCore's technology directly into the Facebook server stack."
PrivateCore was launched in 2012 in Palo Alto and specializes in protecting servers against malware and other kinds of intrusions.
Private Core's Oded Horovitz said in a blog post that the two firms "have an aligned mission."
"Since the beginning, we have worked tirelessly on our technology to protect servers from malware threats, unauthorized physical access, and malicious hardware devices," he said.
"Working together with Facebook, there is a huge opportunity to pursue our joint vision at scale with incredible impact."
Terms of the deal were not announced.