Fontana was born in France 20 years to the day after the atomic bombing of Hiroshima, and his choice of the artistic name, Megaton, was influenced by this, even though the Hiroshima bomb was only 16 kilotons. He grew up in a Paris banlieue, and after qualifying for a diploma in psychology, was active as an artist, including graffiti. After meeting Jean-Baptiste Mondino, he started working in films.
Megaton has directed Exit, The Red Siren, Transporter 3, and Taken 2. Transporter 3 and Taken 2 received scores of 36% and 21%, respectively, on the meta-critic site Rotten Tomatoes. He was chosen to direct Mathilda, the sequel to Léon, but expressed the opinion that the film was unlikely to be made. He also served as a second unit director for the film Hitman.