Online social network company Facebook's co-founder and chief executive officer Mark Zuckerberg announced on his Facebook timeline Saturday evening that he and longtime girlfriend Priscilla Chan have tied the knot.

Facebook co-founder and CEO Mark Zuckerberg (R) and Priscilla Chan are seen in this screengrab of a wedding photo posted on Zuckerberg's Facebook page, May 19, 2012. [Photo: China Daily via Agencies]

"Mark Zuckerberg added a life event to May 19, 2012 on his timeline: Married Priscilla Chan," read his post. As the photo he posted shows, the young CEO wore a suit jacket at the wedding rather than his trademark hoodie.

The couple tied the knot at Zuckerberg's home in Palo Alto, California. "Zuckerberg's wedding was in his backyard, before fewer than 100 guests, who thought they were there to celebrate Chan's graduation," according to a tweet from a Huffington Post editor.

Chan and Zuckerberg met at Harvard and have been dating for more than nine years. Chan, 27 years old, is an American-Chinese.

The wedding wraps up a busy week for the couple. Zuckerberg turned 28 on Monday, the same day Chan graduated from the medical school at the University of California, San Francisco. On Friday, he rang the bell from Facebook headquarters in California, staging one of the most anticipated initial public offering in Wall Street history.

Facebook's shares, priced at $38 on Thursday, opened at 42.05 dollars on Friday, and closed at 38.23 dollars.

Facebook co-founder and CEO Mark Zuckerberg and Priscilla Chan are seen in this wedding photo May 19, 2012. [Photo: China Daily via Agencies]