Click on the photo below for a gallery of the twins' most adorable moments.
In celebration of Crown Prince Frederik and Crown Princess Mary's youngest children, the royal palace has released the cutest photos of Vincent and Josephine.
In one shot, Josephine is pictured affectionately kissing her brother on the cheek, while a further two photos were unveiled of the twins separately. Compared to their second birthday when Princess Mary served as the official photographer, it looks as if the youngsters have been snapped professionally this time round.
The blonde tots have changed remarkably since they were first introduced to the world. When they left the hospital in 2011, proud father Frederik described the new arrivals as "miracles times two".
The heir to the Danish throne and his Australian wife are also parents to Christian, eight and six-year-old Isabella.