David Marcus, who has been president of PayPal, was named to the new post as Facebook appeared set to focus increasingly on messaging.
The California giant said separately it "accidentally" released a version of a new app called "Slingshot," about which reports have been circulating for several weeks.
Although Facebook did not specify the nature of the app, reports have said it would allow for sharing of photos and videos and compete with some startups offering similar services.
"Earlier today, we accidentally released a version of Slingshot, a new app we're working on," Facebook said in an email to AFP yesterday,.
"With Slingshot, you'll be able to share everyday moments with lots of people at once. It'll be ready soon, and we're excited for you to try it out."
The appointment of Marcus also comes with Facebook preparing to absorb the popular messaging service WhatsApp, in a deal worth a whopping $19 billion that was the biggest acquisition ever for Facebook.
Facebook's strategy appears centered around breaking up its service into separate applications that can create their own customer base.
The company earlier this year split off its Facebook Messenger service as a standalone app.
"Messaging is a core part of Facebook's service and key to achieving our mission of making the world more open and connected," said a Facebook statement announcing the Marcus appointment.
"Every day around 12 billion messages are sent on Facebook... We're excited by the potential to continue developing great new messaging experiences that better serve the Facebook community and reach even more people, and David will be leading these efforts."
The statement said Marcus "is a widely respected leader in the technology industry with a track record of building great products.... David taught himself to write code at the age of eight, and he launched his first startup at the age of 23."
In his own Facebook post, Marcus said Facebook chief Mark Zuckerberg persuaded him to take the new job.
In a separate statement, eBay said Marcus is leaving the company on June 27. He joined the company in 2011 and took over as head of PayPal the following year.
PayPal, which allows people to make a variety of financial transactions including online payments, accounts for 41% of eBay revenues and had 148 million users at the end of 2013.