The Bat Signal lit up the night in cities around the world, including New York City.
The signal projection was broadcast on the side of the Domino Sugar Refinery in Brooklyn.
Batman writers were there to hold a signing and panel discussion.
The spire of the Empire State Building was also lit up in Batman yellow and white.
Batman Day is celebrated each year on the third Saturday of September, and this year marks the Dark Knight's 80th anniversary.