Zuckerberg founded what was then called “The Facebook” in his college dormitory in 2004. The service was at first limited only to Harvard students before expanding to other Ivy League universities.
He is due to deliver the university's commencement address, a speech given to graduating students, later on Thursday.
After receiving the honour he posted a photo of him with his parents Edward and Karen Zuckerberg.
Zuckerberg returned to the room where he built Facebook along with his co-founders, Dustin Moskovitz, Eduardo Saverin, Andrew McCollum and Chris Hughes.
Zuckerberg and his wife Priscilla Chan also filmed themselves touring the old dorm rooms and reminiscing about their time at Harvard in the 23-minute Facebook Live video
On Wednesday, he said his upcoming speech would "share what I've learned about our generation and the world we're all building together".
Zuckerberg took a dig at Trump, adding: 'It says something about our current situation that I can't even say his name because I don't want to put him at risk'
Facebook CEO Mark Zuckerberg returned to Harvard with a message on fighting inequality and taking risks in the name of innovation. Zuckerberg, who, like the graduates, is a millennial, started Facebook in his Harvard dorm room in 2004. He dropped out the following year and returned Thursday to receive an honorary degree.
12 years later, today he finally has received his Harvard University
Even after the company moved its headquarters to California, Zuckerberg continued to be enrolled at Harvard until he dropped out in November 2005. "I'm not coming back" he told the university paper The Crimson.
The billionaire CEO received a cheer from the crowd when he was given an honorary Doctor of Laws degree on Thursday at the Ivy League school
Zuckerberg said back in 2005 that he would never return to Harvard after dropping out to focus on Facebook
The Facebook CEO greeted graduating Harvard students at the Ivy League school on Thursday
The Harvard dropout smiled as he was introduced to the crowd before being presented with his honorary Doctor of Laws degree
His honorary degree comes 12 years later, a little quicker than it took Bill Gates, another famous Harvard dropout to get his. Gates, who left to found Microsoft in 1975, did not receive his honorary degree until 2007.