Briefly, he rebelled against family tradition and took up painting in his early twenties. For financial reasons he eventually had to leave Paris and return to Belgium where he gradually built his reputation, eventually moving to Brussels and winning awards.
His most interesting period was the 1920s and 30s when he painted women dressed and undressed. Below are examples of his work. In case you are viewing this at the office, be warned that the nudes are at the bottom, so be careful how you scroll down.
From around 1900.
Watelet could capture personality.
Interesting pose and setting.
The 1920s facial makeup he depicts makes this young lady more artificial looking than the one in the previous image.
Another interestingly posed subject -- nude, but not obviously so.
This seems to be one of Watelet's later works where he simplified his subjects faces and other details.