Willie Hernandez already had IBM, Amazon.com Inc. and Hewlett Packard on his stellar resume. Now he’s added another big firm: Facebook Inc., which he credits with a global reach that can change how communities—no matter how far apart—interact with each other.

Hernandez joined the Menlo Park, California-based firm this week as director and associate general counsel of product. He will lead the legal team for Facebook’s core app. His first day on the job was June 29.