He announced in July that he and wife Priscilla Chan were expecting a baby girl following three miscarriages.
In his post Friday, Zuckerberg said the couple is "starting to get ready" for their daughter's arrival but didn't indicate when she is due.
Facebook, which is based in Menlo Park, California, offers its U.S. employees up to four months of paid parental leave. It's among several high-tech companies that offer generous benefits around childbirth.
Netflix said in August it was giving U.S. workers up to a year of paid leave following the birth or adoption of a child. Adobe Systems and Microsoft bolstered their parental benefits following the move.