According to a Twitter message Friday from Harris that was confirmed by his publicist, the actor and his partner, David Burtka, welcomed twins this week.
Harris tweeted, "Babies!! On 10/12, Gideon Scott and Harper Grace entered the Burtka-Harris fold."
He added, "All of us are happy, healthy, tired, and a little pukey."
The 37-year-old actor announced earlier this year that he and Burtka would become parents of twins.
He didn't say whether they were adopting or using a surrogate.
Harris, who plays Barney on the CBS sitcom, won an Emmy Award this year for a guest appearance on "Glee" and shared in another Emmy for the Tony Awards, which he hosted.