Giannandrea specializes in machine learning and worked at Google since 2010. Apple has struggled to bolster its artificial intelligence operations in recent years with its Siri digital assistant.
"Our technology must be infused with the values we all hold dear ... John shares our commitment to privacy and our thoughtful approach as we make computers even smarter and more personal," Apple CEO Tim Cook said in an internal email to Apple employees obtained by The New York Times.
Industry writer Joshua Fruhlinger analyzed data recently suggesting that Apple was ramping up its hiring to improve its AI platform. Five days ago Apple had 161 job listings with the term "Siri" in them posted, according to Fruhlinger.
Siri is a pivotal lynchpin in the company's services ambitions as hardware sales slow amid a stagnation in innovation.
Apple shares have declined 1.77% year to date and were falling more than 1% on Wednesday.