De Blasio took the oath of office moments after midnight Wednesday in front of his home in Brooklyn.
The ceremony was captured on video.
View this video on YouTube
"This is the beginning of a road we will travel together," the new mayor said after swearing in.
De Blasio's inauguration ceremony will be held at noon Wednesday where he'll be sworn-in again by former President Bill Clinton on the steps of City Hall using a Bible once owned by President Franklin Delano Roosevelt.